So you have got a bluetooth headset thats not A2DP compliant and you want to listen to music via your headset. If you have the new rom you can simply activate the lock function and hit the button on your bluetooth headset which opens the audio gateway, open windows media and listen to files via ur headset. Or if you dont have the new rom or you simply do wanna go through those few steps, follow these instructions. First if you dont have the newest version of microsofts .net framework u can download that from
HERE (note: this has to be installed for the BTToggle program to work), unzip and install the .cab onto your phone (in main memory), then you can the download the program attached to use to open and close the audio gateway. Simply extract the .cab and install. Once installed on your device simply run the toggle program and its opens the gateway to listen to music, toggle the program again and its back to only being used for calls.