It would be very unwise to try to use Limewire if the school prohibits it. Get your own Internet if you really need it.
You might risk losing your (free ?) internet forever, if you keep trying to cheat their system. + you might not be the only one effected. If my school they have shut the connection off, and only turn it on for students that need it for school purposes.
I asure you that after a few days like that, you will be hated if anyone finds out it was you.
Incase anyone starts to wonder if it was my fault, it wasn't