Putting a Tilt 8925 on T Mobile

[LittleBreezes]

Hello all, I have an unlocked AT&T Tilt (8925). I would like to be able to use it on T Mobile here in the U.S.A. Putting a T Mobile SIm into the phone does result in the phone showing 100 percent T Mobile and voice calls seem to come in and out just fine. However, in modem settings under manage current setting I see one entry for Media Net. Can I create a new modem entry to use the T Mobile data network so that Internet Explorer and over the air activesync will work? If so what settings do I need for T Mobile? I would assume I would need a modem dialing string, username and password? What other information would I need to know and where can I obtain this information?
Any help would be greatly appreciated.
thank you
Frank