I seem to recall that there was a feature added to Hijack which would switch to the aux-in when the mobile phone mute line (green wire on the empeg sled's wiring harness) went high. So the option of adding the car kit to the empeg's aux-in is do-able I think. However you must use Hijack and configure the player properly in order for it to work. I don't recall what the configuration options were exactly, though, so dig through the Hijack section of the FAQ to find out.