Is it possible ( with or with out any coding) to use either the microphone input or the audio in meant for the tuner at the same time as either the player or the Aux in source.

I would like to connected my iPaq up and have it's sound played over the top of the normal player output. at a constant volume independent of the players volume control.

The plan is to run Sat Nav on the Ipaq with the audio directions mixed in with the normal player output, but so that i can turn down the player and still have the directions at the same volume.

Any ideas?

Thanks
Russell