I am attending college right now, and I have gone with Xbox Live long enough

Here is the problem, I connect to the internet by plugging into the wall using an ethernet port. We use something called ResNet. I am on a Macbook Pro. I figured that it would be as simple as plugging my ethernet cord from the wall into my Xbox 360. I did this and get an MTU failure. So I talked to the IT department and they said that I could only have one device registered to a room at a time. I am assuming they are doing this using a MAC address. So I wondering if two things would work?

1. Could I get an ethernet switch or an ethernet adapter? Would this trick the system into thinking that my xbox has the same MAC address as my computer?

2. Could I just tell Resnet I got a new computer, send them a "new" MAC address which would actually be my xbox 360s MAC address, and then change the MAC address on my computer to the same one that is on my Xbox 360?

Those are just thoughts coming from a guy with limited knowledge on the subject. Any other advice I would be willing to try. It's ridiculous that they just can't register my xbox 360s MAC address for all the money I pay for the school.

So please I need help.

You CAN try routing the xbox 360's data through your pc via xboxconnect hopefully this would use the same MAC address as your pc's NIC, However im not sure whether it supports genuine xbox live account holders lol t'is worth a try though, but one thing - you may need a crossover cable rather than an ethernet cable for your xbox to interface with the pc.
EDIT: you said you were on a mac, im not sure whether the xboxconnect software supports os/x or whatever os is on there, i believe it was made for windows, ill get back to you on that
SECOND EDIT: The software doesn't support the mac, you could try a windows runtime environment simulator such as vmware, bootcamp, parallels, i think, however it may be a little elaborate just to get xbox 360 working, though telling the guys in charge you have a new pc, then giving them the MAC address of your xbox360 is actually a good idea, i dunno whether they will run a check on it though :S

Yeah it does not work with xbox live. I need xbox live to work.

Well, the MTU error is down to your server's settings, MTU should be set to 1500 for your xbox 360, if you are not network admin, you cannot change this setting .You COULD get a mobile broadband stick and game via this, but it would be VERY expensive to do so, otherwise you could try persuading the guys in charge, but this, in my experience at least, doesn't work

Can anyone help me?