[eenieMINI]

I would delete entirely the key that says Extension and the key that says status.. as those keys are not in my registry (I deleted extension and never had status) and I have no issues tethering.

Now, I'm not familiar with MAC's at all but the first thing we need to see on your Diamond is that of course you have bt enabled, then go to ICS program and select BTPan and Sprint then click "Connect" at the bottom left... what do you see in your phone screen then? You should get a pop up saying you need to be visible (if you weren't already) Then you might see a screen wanting you to log into sprint .. clear all 3 boxes and check the save password (yeah all is blank) then OK. Now you should have a
"Status: Device Setup finished. On the PC, Connect Bluetooth PAN"

So now if you get that far your phone is ready, so go to MAC and do whatever you do to connect to a bluetooth network. On my PC I go to Managae Network Connections and click on the BT icon and click Connect.

If you don't get that notice on the ICS screen we have more to do with the phone, less to do with the MAC yet.