The shrouds actually come off fairly easily. The ones I've seen are typically just held on by friction (and maybe some reall light glue). So you can just pull the shroud right off.(Of if that fails, you can very easily cut the shroud).
[EDIT] Or look here:
http://www.chiefdelphi.com/forums/sh...threadid=22798
[/EDIT]
On a side note: Why do you say "Now only a bit of the Edubot (software) is like the real robot."
You should be able to bascially copy your UserRoutines.c from one to the other with only a few minor changes (such as there being not PWM_inXX on the full size).. Beyond that the values you get from the Full Size OI Joysticks should be the same as the ones from the RC controller (though the RC controller may have a more limited range, YMMV).
If you need clarification on what I just said, feel free to ask..