heh, as a network admin for a school i laugh at ya kev
What we have set up is a linux box with no external access at all for the students. The only access they get is to a squid cache on the linux firewall, which makes it good since the only method after that to get outside is to use a program called http-tunnel which u can get at
www.http-tunnel.com
The one big downside to http tunnel is that if you use the free service, you get limited to about 1.5k a second thruput, and if u pay the bit for the uncapped service u only get about 12k a second
So there may be little you can do about things Kevin, depending on how they have modified the firewall, VPN might not be an option.