i've done a LOT of study and work on unattended installs.

in theory, if you have an unattended cd ready to go, this should be really easy to do. here's the steps it would require. (this is assuming you know the basics of creating an unattended install)

copy your current LS folder to:
[cd root]\$OEM$\$1\
and the litestep dir will be copied to the root of your c: drive.

next you have to have a .reg file ready to go to import the key to tell windows to change the shell to litestep. it's easy to make, just make a text file with this inside it:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon]
"Shell"="c:\litestep\litestep.exe"

and then change the extention of that text file to .reg

place that in your $1\install dir and make a callout from your installation batch file to that reg file and voila! you're done.

let me know if this is confusing, i can probably explain more if need be.