Yes, quite possible. Getting it to return to the state it was before your phone rang is more dificult. If you don't have a tuner, hijack can easily change the onmute into the button presses needed to switch between aux and player. If you use a tuner, it should be possible to get it to switch between the player<->aux and FM<->aux properly, though I never got it to work. The empeg always returns to the last FM station when you press tuner, so getting it to switch AM<->aux properly doesn't seem to be an option.

I've got a ck3100. I've posed my various irtranslate sections before, if you look up the on_mute button code and search for it, you should be able to find it easily.

No matter what you do, you'll still only have a 95% success rate with the onmute translations. Occasionally the empeg will miss a button press and you'll have to fix it manually.

Matthew