I have figured out how to get a Palm-branded GPS to work with TomTom.  Last year I purchased a package for my Treo 700w that had TomTom and a Palm Bluetooth GPS.  I upgraded to a Sprint Mogul from my Treo a few months ago and I still wanted to use my GPS.

To get the GPS to be recognized, go into the Bluetooth settings and create a new connection to the GPS.

Add New Device
Enter 0000 for the code
Click on the COM Ports tab
Create a New Outgoing Port
Select the Palm GPS and choose a number (I chose 0).
Your software should pick it up now.  TomTom doesn’t seem to work on a non-palm device, but you may be able to get an upgrade.  Your maps are still registered to you.