HOWTO make an Xbox 360 get a DHCP address from OS X Internet Sharing

This had me puzzled for a bit: I set up a TV and Xbox in our hotel room and tried to get on Xbox Live through the wireless connection on my MacBook Pro. The Xbox stubbornly refused to pull an IP address from the Mac. After a little Bing-fu I found this article, which explains how to fix it. It works like a champ!