Sharing your Macbook Pro Connection with your Xbox 360

For those who don't want to buy the wireless adapter, you can do it with your mac!

I copied these off the net - but I had to make one slight change for my own setup - my router was 196.168.2.1

Before you start configuring, open up Terminal (in Applications -> Utilities) and type "ifconfig en0" (zero, not a capital-o). You're looking for the bit that says "inet xxx.xxx.xxx.xxx". In my case, the number I get here is 192.168.2.1 Second, note down the IP address of your wireless router, which in my case is 192.168.0.1

On your Mac
Connect your Mac to your wireless internet connection
Connect your Xbox 360 to your Mac via Ethernet
In System Preferences -> Sharing, enable Internet Sharing between your Airport and Ethernet connection
On your Xbox 360
Start up your Xbox and navigate to the Network settings menu
Under IP address, enter the number you got from the "ifconfig en0" command earlier on, but with the final number one place higher. In my case, I take the 192.168.2.1, and input 192.168.2.2 in the IP address box on my Xbox 360.
Under subnet, input 255.255.255.0
Under router/gateway, enter the number you got earlier from the "ifconfig en0" command. In my case, that's "192.168.2.1"
Move onto DNS. Enter the IP address of your wireless router (in my case, "192.168.0.1") in both the primary and secondary IP address fields
Leave PPPoE and Advanced settings blank (i.e. OFF and Automatic)
You should now be able to connect to Xbox Live via your internet sharing Mac
If you manage to get this method, or a similar method working, don't forget to drop by the comments thread to record your experience!