If I am using a PDA for Navigational purposes.
Is there a way to feed the sound from / make the system cut to the PDA?!

In other words:
While I'm listen to the radio have the directions cut the music and then return to the music.

Radio --> Mute --> "Turn left" --> un-mute --> Radio

* I Plan on using a Ipaq or MIO 168.
~Alon