Hippy...you're a bit 'off' with '2'.
For a good Shell Manager/switcher [as opposed to a theme switcher in LiteSTEP], use ShellON.
It handles registry settings in NT/XP/2K, and saves even messing with system.ini in 9x...
As for changing themes, 'IF' they are OTS-compliant ones, then there's not very much involved with it at all. However, for many years, LS themes have NOT been set up this way, but can differ quite dramatically, being totally incompatible without 'experienced' coding conversion.
If you are in OTS themes, LSCP.exe is a quite functional method of theme switching, being the method I've used since switching to OTS, without any troubles at all...