I disassembled the T/W and found a perfect place to put the Bluetooth module, now its a matter of building a shielded wire harness for the battery and connection to the phone's 2.5mm jack from the inside (in case you want to use the original headset w/out bluetooth) and the battery voltage for both the T/W and Bluetooth is the same (they will have to share power), given the T/W is good for about 11hrs, I suspect 5hrs of talk time w/Bluetooth is reasonable, and I can more than live with that.

I have to put kapton tape to electrically isolate the board from the shielded box on the T/W main board (28mm x 42mm). I need 2.9mm of height (there is 4.2mm) and 21mm x 34mm for the Bluetooth board and I have 1.3mm of gap still left, I plan to use thermally conductive grease and a aluminum plate adhesive mounted to the plastic back of the T/W so that it will sit on top of the Bluetooth module to remove any excess heat that might develop from module.
I also need to adapt the module turn-on/off button (I have to think about how to engineer it so to look factory made).

Once I have all the materials built It should take about an hour to do.