Xbox live on campus network

I'm trying to figure out how to get xbox live via my campus network. We can all play together over the network, but we can't get "out" to get live. I've heard it's something to do with it not being able to recognize the xbox's IP address. I asked him about it and this is what he said :

"We do not support the use of Xbox on campus. However, that does not mean that it will not work, it simply means that we cannot help you get it running if you can't get it to work. Some students have been able to get it to work by using Internet Connection Sharing on their desktop to serve the connection to their Xbox. In effect, the Firewall client on your computer handles the username/password authentication that is required for communication with internet-based networks, something that the Xbox can't handle. When you set this up, you MUST make sure that you are not serving the connection to any other device on the network, and you MUST register the mac address on the network (use the DHCP registration here: http://terrier9 to do this.)

So if u guys have any questions about specifications or anything let me know. Thanks.

Nobody has any ideas? Thought u guys knew everything ;)

Well the dude obviously told you EXACTLY how other people set it up and got it to work. Ever think of trying that?

just out of curosity, what is the ip addressing scheme that your school uses?? i know mine lets us get a real internet one, but if they are doing NAT'ing then you are most likely screwed