College Dorms no compatiable with xbl, need to spoof mac address will pay for help

Alright so I'm at school and my school has a 802.1x secure single time login internet setup, and of course xbox doesn't have a browser so I can't connect. I have been looking at all forums for the last 3 days this is what I have came up with but still not sure exactly how to do it.

I have a macbook pro.
I connect that to my xbox with an ethernet cord, my macbook is connected to the wifi.
I now need to somehow spoof my network and use the same macaddress and ip address on my xbox, so it thinks its a registered device. (no idea how to do this).
If somebody could spend the time and walk me through this, and succesfully get me connected to the internet I'd much appreciate it.
If there are any other ways like buying a router (take note that all ethernet ports have been shut off) then i'll do that.

$10 paypal'd to whoever can help