for the windows registry problem there is a quick fix:
* at your home (I supposed you have the game installed there) :
click on start, click on run , writte "regedit".
search the game folder there (registry, not game files).
for example:
this is the folder for starcraft (at the registry)
HKEY_CUARENT_USER\software\Blizzard Entertairnment\starcraft
well, when you locate your game folder , hit "right mouse click on the folder" and then click on "export" it will export the folder and the parameters insede the folder to a file (filename.reg")
if you run the game from a different computer location ( for example, at your computer you run the game installed on (C:\), but at the school you run the game from a flash drive (H:\), you only have to edit the .reg file with notepad and change the game directory to the correct one)
then put the .reg file at the flash drive and go to school.
* at school computer: instert the flash drive , Run the .reg file, and run the game exe file, enjoy ^^
anyway IDK if the school computer will let you to insert modifications at the windows registry, anyway I hope you have luck
