is there any way of enabling the FM transmitter to turn on AFTER the call has been accepted, similar to the way you can turn speakerphone on and off, but perhaps through a status menu? currently, it is possible to turn it on and off after the phonecall has been accepted, but the sound doesnt route through FM.

I don't use my n900 for music, and there is no point in turning it on every time i get in the car, just in the rare event i happen to get a phonecall.