You could try using batch files (or shortcuts) in your startup folder (if there is a startup folder that is :D)

In the ls users startup folder: C:\Liteste\litestep.exe (or whatever)
in everyone elses: explorer.exe

That might work more "seemlessly" than a shell switcher ;)
(Plus I dont think there is any reg entries that need to get changed for shells to work on 9x, right?)

ps: Also youll need to set the shell= thing in system.ini (?) to something invisible...