The 360 without the wireless adapter ether the official one or one of the 3rd party supported wifi adapters will not work for using your mogul as a wireless modem.
If you plug your smart phone into the 360 the best its going to do is let u listen to music or watch stored videos off of it.
I could be wrong but your best bet is to dl and try out the ics .21 app and set your phone up in it to be a usb wifi adapter that would be the only way to do i then just join a wireless network with the 360 and play away.
Other option is to get one of the supported wifi adapters to plug into the 360's usb port and try that way. Using the same app set it to be a wireless hotspot for the 360 to connect to AdHoc network.
Here is the xda post explaining all that the app can do
http://forum.xda-developers.com/showthread.php?t=377047