connecting xbox through wireless provided by macbook

[jinbacanaca]

I know your first thought is wireless to mac, ethernet from mac to xbox. This is different. Because of the way the internet is set up in my apartment and I don't want to buy a router what I'v had to do to get wireless is run the ethernet from the wall to my macbook and use my macbook as a wireless access point. Im trying to connect to said access point with my xbox 360's wireless dongle. The xbox will accept the password and attempt to make a connection but for some reason it fails to connect to the access point. Any ideas?

Also i have the access point is wep 40 bit encoded with a 5 letter password and my itouch can run off the access point just fine. I tried using it un-encoded but it still didn't work.