Things you'll need.

A hotel / College
A ethernet cable (that will reach your xbox near the TV)
An Xbox 360
A computer / laptop with an ethernet port

Here's how to do it:

Fire up your laptop and connect to the WIRED internet. Turn your wireless OFF!

Open an internet browser and accept the agreement and enter the code if given. Once successful, make sure you can browse the general internet.

Now close the internet browser, and click start > run and type in "CMD" and enter to bring up a command box.

Type in: IPCONFIG /ALL
Hit enter

scroll up a bit until you find this:
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Make note of your Wired LAN adapter's Physical address. note, only the following numbers are valid:
1, 2, 3, 4, 5, 6, 7, 8, 9, 0 (zero), A, B, C, D, E, F

Next, unplug the network cable from your laptop or computer and connect it to the Xbox.

Start up the xbox.

From the home screen, go all the way right to "settings", Go into "system"

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Choose "network settings"
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Choose "Wired network"
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Choose "Configure network"
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Your basic settings should be set to automatic. The ip numbers here are irrelevant.

Go right to "Additional settings"
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Go down to "Advanced settings"

Choose "Alternate Mac Address"
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Enter the MAC address (physical address of the laptop's ethernet address) here.

Once it's set... back all the way out to the home page and simply "Connect to Xbox Live"

Hope this helps a lot of people it certainly helped me when I went to College!