Wel actually I've got 2 belts like that (one I am using with my Suunto device and a spare one) so I also thought of hooking up the spare one to my N9.

What I thought of trying, is to gut the belt and a bluetooth headset and wire up the BT transceiver to the belt to get it transmitting over BT.
It's bit of a hacking experiment, but I have not got any time yet to do it.