I just got mine working and thought I would share. I done this with my MacBook Pro running 10.5.x and my TMobile 8310. Any questions/comments are welcomed.
1. Download Fibble's modem script and be sure to donate if you can.
You can find it here.
2. Follow the instruction and load the modem scripts.
3. Pair your BB to your Mac
4. Goto system preferences > Network
5. Choose Bluetooth and enter you Data information as shown (this is for TMobile) User/Pass - guest/guest
6. Then select Advanced and add the info from this screen
7. Click apply and give it a try!