Auxilary output and Bluetooth?

I am wondering if it is possible to plug in the phone to either my truck's aux input, or my motorcycle helmet's cardo system for use of the MP3 player, and still be able to use a bluetooth headset? I know you can't make a phone call and listen to music at the same time, but if I could get just the media player to play through the auxilary port, then when the phone rings, mute out, and have the bluetooth headset work for the phone call without unplugging the aux plug my life would be much easier.

Any thoughts on how this could be possible?

Thanks

Apparently it works.

I have my earphones plugged in right now, paired my chatterbox xbi2 (bluetooth in helmet), while media player was on (through my headphones), I dialed a call, my headphones shut off, and the xbi2 speakers in my helmet were ringing.

Thats odd. If I plug in my earphones, then hit the call button on my Cardo Scala in my helmet, it goes into the earphones, not my bluetooth helmet. Same thing if I plug the earphone jack into my truck and have my normal bluetooth piece in my ear. Hit the call button and it goes through the speakers in my truck, and my mic and ear piece on the bluetooth doesn't work. Maybe it is a operating system update that sprint hasn't released yet and verizon has. Thanks for checking though.