Simple -- set up a VPN with appropriate routes on a computer at your home, so that when you connect to it all your traffic is redirected over your home Internet connection.
As added benefit, the school will not be able to monitor what you do over the VPN tunnel -- they will only be able to see the total amount of encrypted traffic between you and the VPN server, with absolutely no clue what it contains.
OpenVPN only requires one open port for the tunnel and can be configured to use any, so it will work in almost any situation. The only limitations are that you must have an always on computer with an unrestricted connection to host the server, and some networking skills to set it up.
