I thought it would be as simple as turning on Internet sharing and plugging in an ethernet cable, but alas, the Xbox refused to acknowledge the connection. It agreed that a cable was connected, but steadfastly refused to get out to the `Net. After a few hours of frustration, and much Googling, here are the two "gotchas" to look out for:
- If you're using an older Mac, then you must use a cross-over cable, not a standard patch cable. This is easy to identify. With both your Mac and your Xbox connected, open the Network control panel. Make sure that you're showing the Network Status section. If Built-in Ethernet's status light is red, you need a cross-over cable. If it is yellow or green, you're okay.
- For whatever reason, the Xbox will not accept DHCP info from the Mac. Everything else I've ever tried will, but not the XBox. Monkeying with bootP or NetInfo is more than I want to tackle. The workaround is to manually enter the IP info for your Intenet Sharing Mac's subnet in the XBox live menus. Unless you've made changes, your info should be the same as mine:
- IP: 192.168.2.x (x being the number your want to give your Xbox; anything greater than 1 will be fine.)
- Subnet mask: 255.255.255.0
- Router: 192.168.2.1
- DNS: You'll need to get this from your ISP, everyone's is different)
[robg adds: I haven't tested this one, as I don't have an Xbox.]

