I just set up a partnership between the two and the Mac asks me if I want to add the PPC as a network connection option. But that's a Mac... it just works! LOL
I bet with some playing you can figure it out... and maybe a few google searches. Here's hoping.
I did the same when I had my BB pearl and Macbook on osx 10.4 and 10.5.
It required running a script I got off the net, and on T-Mobile tethering is not even discussed in the TOS.
I went to 10.6 Snow Leopard on my Macbook and lost tethering via bluetooth with the BB, no real problem since I switched shortly thereafter to AT&T and the iPhone 3G (wife got a 3Gs, lucky gal).
I was able to Set up a tethering profile on my iPhone using blackrain, without opening it up to viruses and hacks. I can tether via USB or bluetooth now.
As I recall my wife was able to USB tether to a blackberry, but not bluetooth on her PC. I forget if that was a non-bluetooth computer or a limitation of the PC.
in anyway, this covers what I did on both types when we had BB
blackberrycool.com/2009/03/10/how-to-tether-your-blackberry-for-free-via-bluetooth-mac-and-pc/ (add w w w)
My wife and I are F1 nuts, and she hopes to DVR/slingbox the Canadian GP from our house to Ft Wilderness, I may have to rent the modem that one day so she can watch it on the computer. I am glad you can do so in the partials now.