Walker, first you'll need to have your phone's WAP settings configured to accept T-Mobile's WAP.
Click Here to get that out of the way.
Next, you won't be able to download games through T-Mobile because it is not a T-Mobile supported phone. You should try what Sony Erricson suggested and go through a third party provider.
Third party providers are outside services that sell games, ringtones, and wallpapers for your phone. They are not connected to nor affiliated with the service you use. The third party provider bills your cell phone company, and in turn, your cell phone company bills you. In your case, you will lose minutes instead of money. Try googling the terms "Jamster, dadamobile, or mQue." Those are the most common ones I see on people's bills.
It is VERY VERY important that you read the terms and conditions of those 3rd party providers. They'll most likely offer you 1 free download, however, they will automatically send you AND bill you downloads until you have cancelled with them. A lot of people get slapped paying huge amounts of money when they start to mess with 3rd party providers, so make sure you read the terms and conditions with them and make sure you know how to cancel with them also.