I don't know what LUA is, but I've done this (some time ago):
add this to the SciTEGlobal.properties:
import litestep
Now, create the "litestep.properties" file:
# Define SciTE settings for Assembler files (IA32 MASM and NASM)
# Originally by Black Horus blackhorus@gmx.net 2002
# Updated by Kein-Hong Man mkh@pl.jaring.my 2003-10
# Masm files
file.patterns.asm=*.rc;*.mz
filter.asm=Litestep configuration files|$(file.patterns.asm)|
lexer.$(file.patterns.asm)=asm
# litestep 0.24.7RC1
litestep=otsmajorversion otsminorversion themename themeauthor configdir \
lsimagefolder lsnoshellwarning lssetasshell include \
tilewindowsh tilewindowsv cascadewindows minimizewindows restorewindows gather \
unloadmodule reloadmodule execute run about none recycle reload refresh logoff shutdown switchuser quit confirm alert clearlog
# netloadmodule-2.3
netloadmodule=\
netloadmodulesite netloadmodulepath netloadmoduledocpath netloadmodulezippath netloadmodulealiasfile netloadmodulealwaysusefolders \
netloadmodulenodownloadstep netloadmodulenoinstallstep netloadmodulenoloadstep \
netinstallmodule netloadmodule netloadmoduletestmessage netloadmoduleonload netloadmoduleonfail \
netreloadmodule netunloadmodule netuninstallmodule netloadmodulebatch
# mzscript-0.9-beta_12
mzscript=\
mzscriptfile mzvarfile mzscriptusestep mzbangchar mzlistseparator mzautosavevars mznostartonrefresh \
varset varremove varshow varrun varadd varmul varmod varint varrnd varsaveall vardump \
ifexist ifnexist ifeq ifneq ifeval \
msgbox exec setlistsep scriptremove pause \
script exec start bang exec exit label goto gotoif
# jdesk-0.73
jdesk=\
jdeskworkarea jdesksetworkarea jdeskresetworkarea jdeskdesktopfolder jdeskdoubleclicktime jdeskclearworkareaonexit jdeskrecycleonrezchange \
jdeskdisablembutton1 jdeskdisablembutton2 jdeskdisablembutton3 jdeskdisablembuttonx1 jdeskdisablembuttonx2 jdeskdisablemwheelscroll jdeskdisabledoubleclick \
jdeskmbutton1 jdeskmbutton2 jdeskmbutton3 jdeskmbuttonx1 jdeskmbuttonx2 jdeskmwheelscroll
# rabidvwm-1.1.1
rabidvwm=\
vwmpos vwmx vwmy vwmsize vwmwidth vwmheight vwmdesks vwmdesksx vwmdesksy \
vwmselexpand vwmdeskborder vwmusefaketrans vwmtransparent vwmconstantupdate vwmusetransblt \
vwmwincolor vwmwinbordercolor vwmwindarkcolor vwmwinlightcolor vwmwinbevel vwmwinalpha \
vwmtitlecolor vwmtitlebordercolor vwmtitledarkcolor vwmtitlelightcolor vwmtitlebevel \
vwmbackcolor vwmbackbordercolor vwmbackdarkcolor vwmbacklightcolor vwmbackbevel vwmbackalpha \
vwmflashcolor vwmflashbordercolor vwmflashdarkcolor vwmflashlightcolor vwmflashbevel vwmflashalpha \
vwmselcolor vwmselbordercolor vwmseldarkcolor vwmsellightcolor vwmselbevel vwmselalpha \
vwmbevel vwmbevelwidth vwmnoborder \
vwmbackbmp vwmbackborder vwmbacktile \
vwmselbmp vwmselborder vwmseltile \
vwmwinbmp vwmwinborder vwmwintile \
vwmtitlebarbmp vwmtitlebarborder vwmtitlebartile \
vwmflashbmp vwmflashborder vwmflashtile \
vwmflashtitlebmp vwmflashtitleborder vwmflashtitletile \
vwmshowicons vwmscaleicontofit vwmiconsize vwmminiconsize vwmiconborder vwmforceiconbordertop \
vwmtitlebars vwmtitlefortitle vwmtitlebarheight vwmtitlebarmod \
vwmhidetaskonswitch vwmnoswitchonfocus vwmswitchonanyfocus vwmfocustop vwmfocuslast \
vwmnogathering vwmreturntofirstscreen vwminitialdesk \
vwmmouseleft vwmmouseright vwmmousemiddle \
vwmalwaysontop vwmnoshow vwmhidden \
vwmnowrap vwmdeskspacing vwmsnapwindowondrag \
vwmhovertime vwmdetecttitlechange \
vwmnoshellflash vwmflashcount \
vwmrefreshtime vwmkeepwindowswithparent \
vwmleft vwmright vwmup vwmdown vwmdesk \
vwmgather vwmgatherlost vwmopen vwmmoveapp \
vwmreset vwmmove vwmflash vwmexec vwmsetdesks \
vwmshow vwmhide vwmtoggleontop vwmtoggle vwmtogglehidetask \
vwmaction vwmsticky \
vwmignoretitlechange vwmfix vwmsticky vwmstartwindowsondesktop \
vwmoninit vwmonquit \
vwmonmouseover vwmonmouseout vwmonhover vwmonunhover \
vwmonswitchfrom vwmonswitchto \
vwmonnewwindow vwmonremovewindow vwmontitlechange \
vwmonleftbuttondown vwmonrightbuttondown vwmonmiddlebuttondown \
vwmonleftbuttonup vwmonrightbuttonup vwmonmiddlebuttonup \
vwmonmousemove \
vwmonrepaint \
vwmonmovewindow vwmonsizewindow vwmonflash \
vwmloadinbox vwmloadboxhook \
monitornames vwmonmonitor vwmswitchmonitor
# tasks-0.92b3
tasks=tasksx tasksy tasksheight taskswidth tasksspacingx tasksspacingy \
tasksdirection taskswrapdirection taskswrapcount tasksmaxtiles \
tasksdockwindow tasksdragdistance taskssettimer tasksiconsize tasksdisplay taskszorder taskstransparency \
tasksmbutton1 tasksmbutton2 tasksmbutton3 .syspopup \
tasksemptycmd tasksautoarrange taskshideminappbar tasksmoveall tasksnohints tasksnoicons \
tasksnominimizeonclick tasksnomove taskssort tasksstarthidden \
taskstitles taskstitleminimized taskstitleselected \
tasksusewindowssettings tasksusesystemhook \
tasksboxhook tasksgather taskshide tasksmove tasksshow tasksswitch taskstoggle \
tasksminimize tasksmaximize tasksrestore \
tasksadd tasksclass tasksicon tasksignore taskspix taskswrapcmd \
tasksiconx tasksicony taskspixx taskspixy \
tasksbgcolor tasksdarkcolor taskslightcolor tasksbgimage \
taskstitlex taskstitley taskstitleheight taskstitlewidth \
taskstitleiconx taskstitleicony taskstitlepixx taskstitlepixy \
taskstitlefontsize taskstitlefont \
taskstitlefontcolor taskstitlebgcolor taskstitledarkcolor taskstitlelightcolor \
taskstitlealigncenter taskstitleitalicize taskstitlenoellipsis taskstitleunderline \
taskshighlightminimized \
tasksminiconx tasksminicony tasksminpixx tasksminpixy \
tasksminbgcolor tasksmindarkcolor tasksminlightcolor tasksminbgimage \
taskstitleminx taskstitleminy taskstitleminheight taskstitleminwidth \
taskstitleminiconx taskstitleminicony taskstitleminpixx taskstitleminpixy \
taskstitleminfontsize taskstitleminfont taskstitleminfontcolor \
taskstitleminbgcolor taskstitlemindarkcolor taskstitleminlightcolor \
taskstitleminaligncenter taskstitleminitalicize taskstitleminnoellipsis taskstitleminunderline \
taskshighlightselected \
tasksseliconx tasksselicony tasksselpixx tasksselpixy \
tasksselbgcolor tasksseldarkcolor taskssellightcolor tasksselbgimage \
taskstitleselx taskstitlesely taskstitleselheight taskstitleselwidth \
taskstitleseliconx taskstitleselicony taskstitleselpixx taskstitleselpixy \
taskstitleselfontsize taskstitleselfont taskstitleselfontcolor \
taskstitleselbgcolor taskstitleseldarkcolor taskstitlesellightcolor \
taskstitleselaligncenter taskstitleselitalicize taskstitleselnoellipsis taskstitleselunderline
# taskbar3-0.306_alpha-3
taskbar=taskbarx taskbary taskbarwidth taskbarheight taskbarmaxtaskwidth \
taskbaralwaysontop taskbarstarthidden \
taskbardisableflashing taskbaruserealflashing taskbarrefresh \
taskbarbuttondirection taskbarmaxbuttoncount taskbarusetooltips taskbarnoskinshift taskbarnofontshift \
taskbarborder taskbarbuttonborder taskbarbuttonfontborder taskbarspacing \
taskbariconshow taskbariconx taskbaricony taskbariconsize taskbarusehueing taskbarhuecolor taskbarhueintensity taskbarusesaturation taskbarsaturationintensity \
taskbarback taskbarnormalback taskbaractiveback taskbarminimizedback taskbarflashingback \
taskbarfore taskbarnormalfore taskbaractivefore taskbarminimizedfore taskbarflashingfore \
taskbarfore2 taskbarnormalfore2 taskbaractivefore2 taskbarminimizedfore2 taskbarflashingfore2 \
taskbarskincenter taskbarnormalskincenter taskbaractiveskincenter taskbarminimizedskincenter taskbarflashingskincenter \
taskbarskinleft taskbarnormalskinleft taskbaractiveskinleft taskbarminimizedskinleft taskbarflashingskinleft \
taskbarskinright taskbarnormalskinright taskbaractiveskinright taskbarminimizedskinright taskbarflashingskinright \
taskbarfontshow \
taskbarnormalfontface taskbaractivefontface taskbarminimizedfontface taskbarflashingfontface \
taskbarnormalfontheight taskbaractivefontheight taskbarminimizedfontheight taskbarflashingfontheight \
taskbarnormalfontbold taskbaractivefontbold taskbarminimizedfontbold taskbarflashingfontbold \
taskbarnormalfontitalic taskbaractivefontitalic taskbarminimizedfontitalic taskbarflashingfontitalic \
taskbarnormalfontunderline taskbaractivefontunderline taskbarminimizedfontunderline taskbarflashingfontunderline \
taskbarnormalfontcolor taskbaractivefontcolor taskbarminimizedfontcolor taskbarflashingfontcolor \
taskbarusefontshadow \
taskbarfontshadowcolor taskbarnormalfontshadowcolor taskbaractivefontshadowcolor taskbarminimizedfontshadowcolor taskbarflashingfontshadowcolor \
taskbarfontshadowoffsetx taskbarnormalfontshadowoffsetx taskbaractivefontshadowoffsetx taskbarminimizedfontshadowoffsetx taskbarflashingfontshadowoffsetx \
taskbarfontshadowoffsety taskbarnormalfontshadowoffsety taskbaractivefontshadowoffsety taskbarminimizedfontshadowoffsety taskbarflashingfontshadowoffsety \
taskbarhorizontalfontalign taskbarnormalhorizontalfontalign taskbaractivehorizontalfontalign taskbarminimizedhorizontalfontalign taskbarflashinghorizontalfontalign \
taskbarverticalfontalign taskbarnormalverticalfontaligntaskbaractiveverticalfontalign taskbarminimizedverticalfontalign taskbarflashingverticalfontalign \
taskbarnoflash taskbarremove taskbaradd taskbarhide taskbarhidetasks \
taskbarlbuttondown taskbarrbuttondowntaskbarmbuttondown taskbarlbuttonup taskbarrbuttonup taskbarmbuttonup \
taskbartbutton .select .menu .close2 \
taskbaronadd taskbarondel taskbaronflashstart taskbaronflashstop \
taskbarhide taskbarshow taskbartoggle taskbarsize taskbarmove taskbarmoveby taskbarboxhook \
taskbarlines taskbarshrink taskbargrow \
taskbarhidetasks taskbarshowtasks taskbartoggletasks taskbarswitch taskbarshowpart
# popup2-2.1.6
popup=hotlistname \
popuptitlealignment popuptitleheight popuptitlecolor popuptitlebgcolor popupgradienttitle \
popupfoldercolor popupselfoldercolor popupfolderbgcolor popupselfolderbgcolor popupfolderpix popupselfolderpix popupgradientfolder \
popuparrowimage popupselarrowimage popupnofolderarrow \
popupentryalignment popupentrycolor popupentrybgcolor popupselentrycolor popupselentrybgcolor popupgradiententry \
popupbevellightcolor popupbeveldarkcolor popupnobevel popupnomenubevel \
popupentryfontface popupfontface popupfontheight popupselentryfontface popupselentryfontheight popupfolderfontface popupfolderfontheight \
popupentrybold popupselentrybold popupfolderbold popupselfolderbold popuptitlebold \
popupentryitalic popupselentryitalic popupfolderitalic popupselfolderitalic popuptitleitalic \
popupentryunderline popupselentryunderline popupfolderunderline popupselfolderunderline popuptitleunderline \
popupentryshadowdepth popupselentryshadowdepth popupfoldershadowdepth popupselfoldershadowdepth popuptitleshadowdepth \
popupentryshadowcolor popupselentryshadowcolor popupfoldershadowcolor popupselfoldershadowcolor popuptitleshadowcolor \
popupgradientselentry popupgradientselfolder \
popupsubmenuheight popuptitlepix popupentrypix popupselentrypix popupseparatorpix popupbottompix popupblt popuppaintmode \
popupborderleft popupbordertop popupborderright popupborderbottom \
popupnottransparent popupadaptivewidth popupminwidth popupmaxwidth \
popupoverlapx popupoverlapy popuptextoffset popupmenudelay popupfolderhoveropen popupnotitles \
popupicons popupiconsonright popupdefaulticon popupfoldericon popupiconspacing popupiconsize \
popupdatetimealign popupautoseparator popupshowextension popuptaskswindowcaption popupscrollspeed \
popupentryfontheight \
popupnoclosebutton pinnedpopupnotontop popupnotitletext popuptasksstartpinned \
popup popupfolder dynamicfolder popupdynamicfolder popupimage separator popuptasks popuprun \
remoteamp datetime popupmycomputer popupnetwork popupcontrolpanel popupprinters popuprecyclebin popuprecentdocuments popupdesktops
# timer-0.5
timer=timer timerstart timerstop timerkill timeradd timerupdate timerremove
# one-0.6
one=one .none .focus .minimize .maximize .restore .close .hide .show
# lsxcommand-1.8.5
command=commandx commandy commandoffsetx commandoffsety commandwidth commandheight \
commandnotalwaysontop commandhiddenonstart commandwaitforbox commandnotmoveable commandnocursorchange \
commandbevelborder commandbordersize commandbottombordersize commandtopbordersize commandleftbordersize commandrightbordersize commandbordercolor \
commandtextfontface commandtextsize commandtextbold commandtextitalic commandtextunderline commandtextcolor \
commandbgcolor commandbackground commandstretchbackground commandtransparenteditbox \
commandexplorepaths \
commandhistoryfile commandclearhistoryonstartup commandunixhistory commandhistoryentries commandnewesthistoryitemsontop commandhistorymenuentries commandaddexternalstohistory \
commandassumenetaddress commandsearchenginelist commandsearchenginebrowser \
commandmusicplayer commandscrollwinamptitle commandwinampdisappearsonfocus \
commandcontextmenustandarditems commandcontextmenuabovebox commandcontextmenuexecute commandcontextmenuorder commandcontextmenuautopopup \
commandnowarnonerror commandhideoncommand commandselectallonfocus commandselectallonmousefocus \
commandhideonunfocus commandonfocus commandonunfocus commandnoclearoncommand commandclearonhide \
commandtime commandclockdisappearsonfocus \
commandnotabmicrocomplete commandtabfilecomplete commandnoautocomplete \
commandcommadelimiter commandrpncalculator \
togglecommand focuscommand commandrescanengines commandclearhistory commandshowcontextmenu command \
commandshow commandhide commandbrowsefile commandbrowsefolder commandmove commandtoggletimer commandsettext commandboxhook
# geekamp-1.9.71
amp=winampstartnormal winamppath winampinipath winampstartoldsetting \
loadfilenotopen playnotopen playpausenotopen prefsnotopen playlistnotopen shownotopen librarynotopen \
amp_play amp_pause amp_playpause amp_stop amp_stopfade amp_next amp_prev \
amp_volumeup amp_volumedown \
amp_loadfile amp_loaddir amp_openloc amp_addsong \
amp_moveposition amp_rew amp_rewd5s amp_rewd10s amp_rewd20s amp_ffwd5s amp_ffwd10s amp_ffwd20s \
amp_eq amp_playlist amp_library amp_video amp_togglebrowser amp_prefs amp_editid3 amp_fileinfo amp_mainmenupopup \
amp_ontop amp_show amp_hide amp_display amp_windowshade amp_shadeplaylist amp_shadeboth amp_doubesize amp_easymove \
amp_setvolume amp_setpanning amp_liststart amp_listend amp_jumptotime amp_jumptofile amp_jump10forward amp_jump10back \
amp_repeat amp_shuffle amp_timeelapsed amp_timeremaining \
amp_loadeqpreset amp_startplugin amp_pluginsetup amp_vissetup amp_selectskin amp_reloadskin \
amp_power amp_poweron amp_poweroff amp_restart amp_about amp_ls2k\
# lswchanger-1.2
wallpaper=wallpaperselectmethod normal sorted random \
wallpaper .tile .center .stretch .change .clear .mix .sort
# skinbox-1.0-beta_4.1
skinbox=skinbox skinboxmove skinboxsize skinboxontop skinboxalpha skinboxshow \
skinboxcreate skinboxdestroy skinboxloadboxhook skinboxexec skinboxaction \
skinboxbitmap skinboxedge skinboxtile skinboxcolor \
create destroy mouseover mouseout mousemove hover unhover \
lbuttondown rbuttondown mbuttondown lbuttonup rbuttonup mbuttonup \
lbuttonclick rbuttonclick mbuttonclick ondropfile ondropurl ondroptext
# layercut-1.72
layercut=shortcutdefaultalpha shortcutalphathreshold shortcutnoloadingonstartup shortcutsoundsync shortcutnodisplaychange shortcutupdatepos shortcutprimarymonitor \
shortcutgroupsetalpha shortcutgroupshow shortcutgrouphide shortcutgrouptoggle shortcutgrouptoggleontop \
layercut animation image size speed flags between execution left right middle drop in out \
shortcutbox
cpu_instruction2=
fpu_instruction=
ext_instruction=
register=
directive=
directive_operand=
directive_nasm=
directive_operand_nasm=% ^$ ^@
keywords.$(file.patterns.asm)=$(litestep) $(netloadmodule) $(mzscript) \
$(jdesk) $(rabidvwm) $(tasks) $(taskbar) $(popup) $(command) $(timer) $(one) \
$(amp) $(wallpaper) \
$(skinbox) $(layercut)
keywords2.$(file.patterns.asm)=$(fpu_instruction)
keywords3.$(file.patterns.asm)=$(register)
keywords4.$(file.patterns.asm)=$(directive) $(directive_nasm)
keywords5.$(file.patterns.asm)=$(directive_operand) $(directive_operand_nasm)
keywords6.$(file.patterns.asm)=$(ext_instruction)
fold.margin.width=0
autocompleteword.automatic=0
autocomplete.*.ignorecase=1
open.dialog.in.file.directory=1
save.recent=1
# Default style
style.*.32=$(font.base) ,back:#606060,fore:#000000 {}
caret.fore=#FFFFFF
caret.line.back=#303840
selection.fore=#101010
selection.back=#c08040
# Comments
comment.block.asm=;
# Line number
style.*.33=back:#505050,$(font.base)
# Brace highlight
style.*.34=back:#282828,fore:#ffc080,bold
# Brace incomplete highlight
style.*.35=back:#282828,fore:#FF8080,bold
# Control characters
style.*.36=
# Indentation guides
style.*.37=fore:#C0C0C0,back:#FFFFFF
colour.rc=fore:#a0a0a0,bold
colour.number=fore:#a0c0d0
colour.string=fore:#d0d0ff
colour.flag=fore:#80b0c0
colour.operator=fore:#80a0c0
tabbar.visible=1
tabbar.hide.one=1
check.if.already.open=1
# Assembler Styles
style.asm.32=fore:#000000,font:Verdana,size:8
# Default
style.asm.0=$(colour.flag)
# Comment
style.asm.1=fore:#ffffff
#$(colour.code.comment.line),font:Comic Sans MS,size:8
# Number
style.asm.2=$(colour.number)
# String
style.asm.3=$(colour.string)
# Operator
style.asm.4=$(colour.operator),bold
# Identifier
style.asm.5=
# CPU instruction
style.asm.6=$(colour.rc)
#fore:#0000ff
# FPU instruction
style.asm.7=fore:#0000ff
# Register
style.asm.8=fore:#46aa03,bold
# assembler Directive
style.asm.9=fore:#0000ff
# assembler Directive Operand
style.asm.10=$(colour.flag)
# Comment block (GNU as /*...*/ syntax, unimplemented)
style.asm.11=$(colour.code.comment.box),$(font.code.comment.box)
# Character/String (single quote) (also character prefix in GNU as)
style.asm.12=$(colour.string)
# End of line where string is not closed
style.asm.13=$(colour.string)
# Extended instructions
style.asm.14=fore:#B00040