Hi, I'm on campus, the only way I have found to connect devices that don't support the 802.1x encryption the network uses is to use a windows machine with two network cards (I'm using an old laptop with the built in network adapter and a USB-Ethernet adapter)
Connect the compiter to the Uni ethernet and login using the manual settings detailed on the ITS pages
Plug in the ethernet to usb adapter to the computer and make sure its recognised
Ensure you can get online on the computer and if so, go to adapter settings, right click on the network adapter that is connected to the uni network and choose properties then sharing and share the connection with the other ethernet adapter.
Connect an ethernet cable from the usb adapter to the xbox and see how if it works.
Let me know how you get on
Dom