I believe you may be looking for an app called Tetherberry. I use Tetherberry to connect my 8900 with several of my Mac's. Not sure if it will work the same for your Tour but I would look into it.
I downloaded Tetherberry Trial and still had problems. I am using a Tour and a Mackbook Pro 5,3 on Verizon - with fee paid to allow tethering. If you figure it out, please post a solution.
