Oh, I thought you meant you wanted to enable both wifi and ad-hoc at the same time. If you can't just set up a new network connection and set it to ad-hoc, then your school must have installed security measures against this. Bypassing this would be a violation of their Acceptable Use Policy (AUP...they most likely have one, or should). I've never had to bypass any security methods to do this so I probably couldn't help you.