Well it wouldn't be very difficult if you could manage to setup a VPN so they wouldn't catch you. My school caught some dude downloading a game from a torrent website and was lucky to get off with a warning. The easiest way to bypass this would be to use your phone. I know on Android phones you can install VPN's and torrent clients like uTorrent. With those installed you should be free to download. I take no responsibility if you get caught though.
Millz idea most likely is the best way just like to point out you're downloading on the school network not your own 3G OR 4G connection if you do that.