Networking & wireless: Xbox 360 Shared wireless internet system-link

Xbox 360 Shared wireless internet system-link

I stay in an old dormitory which only has wireless. In my room I have my Xbox 360 wired to my laptop which has wireless, and I share the internet connection so I can get on Xbox live with no problem. My friend down the hall also has the same thing, except he does not have xbox live and only uses the the internet on the 360 to perform updates; therefore we cannot play each other on xbox live.

My friend's room is too far to send an ethernet cable down the hall. I figured that we can play system-link games over the school's wireless internet which the 360s gain access through out computers. I tried playing Halo over the network, and it does not detect.

Any help would be greatly appreciated.