Here is a way to do it:
Log-in to your sprintpcs.com account and make sure you have a wireless web username and password (power vision), they can be found on the main page and then select settings and passwords and look at the lower left hand of the page and you will see it there. If you don't know the password then select the icon under web user password and select a new password. Write these down, you will need them later.
Go to
http://www.mobile-stream.com/usbmodem.html and download USB modem (don't worry, it has a choice for Bluetooth). Install the .prc file onto your Centro by clicking on the file. This program costs $25 (free trial)but it is worth it to me with my truck requiring $$$ Fuel. Go to the program on your Centro and click on the icon. Choose connection type (bluetooth) and then click on enable modem. Your Centro will reboot.
Go to your TT 920 and setup your settings for TomTom Plus services.
Access point: blank
username: Your Vision username you wrote down from sprintpcs.com
password: Your Vision password you wrote down from sprintpcs.com
IP: Auto
DNS: Auto
Number to dial: #777
Log-in: Blank
You are done!
It worked the first time for me. It seems it will work for all the Palm phones out there. Good Luck!