Windows smartphone as a bluetooth modem under OS X?

I’m going absolutely mad trying to get my i-mate SP3i to function as a Bluetooth modem under Mac OS X. I’ve obviously set this up many times before for a lot of different devices, but I can’t seem to get it to work on a Windows Mobile-based smartphone. Some might say that I’m a glutton for punishment in trying to make this happen, and, well, I can’t very well refute that.

If anyone out there has this working with any Windows Mobile device, please let me in on the secret — I’ve reached the end of the Internet trying to find a solution and am done hacking on it for a while.