First, Missing Sync is a must to manage your Blackjack.
However, it is not neccessary for surfing the web while tethered to your MacBookPro via Bluetooth. Tethered via USB is faster, but the Bluetooth connection is fairly respectable.
Here are some very simple step-by-step instructions (because with 10.4.9, it really is that simple):
1. If you have not done so already, pair your Blackjack with your Mac. (You may want to re-pair anyway.) A screen will show up at the end of the pairing process to show that you can use personal area networking with the Blackjack.
2. Turn Bluetooth on, and also make sure you have Show Bluetooth status in menu bar checked in your Bluetooth System Preferences. (If you have not already done so)
3. Fire up Internet Sharing (Start | Accessories | Internet Sharing).
4. Under PC Connection, select Bluetooth PAN, and under Network Connection, select your Cingular (or provider) data.
5. Press Connect, and it should say "Device setup finished. On the Mac, connect Bluetooth PAN."
6. Finally, in the Bluetooth icon in your menu bar, select "Join Network on (whatever your device name is)" and you're all set!