First, go to Control Panel->Phone and Modem and select your bluetooth modem properties. There is a field that you can type in extra initialization string. Put in: AT+CGDCONT=1,"IP","wap.voicestream.com"
Next, in IE or FF, go to properties and set up the proxy settings. Put the following in: 188.8.131.52 for address and 8080 for port. I found that automatically detecting the settings doesn't work. Also, remember to change it back if you're using WiFi or a direct ethernet connection.
Hope this helps!