Simple. Buy any bluetooth dongle which supports audio gateway. Any china made dongle having Widcomm drivers will do. Set your bluetooth device as the handsfree device of your phone. Now, all your audio output from phone will be redirected(streamed) to the PC, and your pc's microphone will become your phone mic.
Your mobile and dongle should support A2DP for stereo streaming.(N73 has A2DP)
But, how do one stream music from pc to phone over bluetooth? Are you talking about FM transmitter?