My HP dv6654us never came with a Bluetooth module... . However, HP offers replacement parts; they'll send me a Bluetooth module + cord. While the removal process is a little convoluted, they say that installing a module is the reverse process. I can't imagine that the mobo would have the Bluetooth connection removed entirely on models without Bluetooth OOTB... what do you think? The repair/modding guide is located here (PDF Warning).

Or to save the hassle, you could just get one of these:

Worlds Smallest USB Bluetooth - Cheap!

Cost me a couple of pounds GBP and works with Mac OS out of the box. The only downside is you use up one of your USB ports in the process.