I found this page explaining how to hook it up:
TomTom GO Manual
That page wants you to set your Bluetooth to discoverable on the Blackberry. Go to OPTIONS, then Bluetooth, click the wheel, and choose Options again. Make sure "Discoverable" is yes. The two should find each other, and the Blackberry will ask for the PIN code. According to the page above, that should be 0000, all zeros.