So.. for integration with other in-car controls, the question is always.. what electrical/wireless interfaces does the car head unit support for such, and is there documentation for the protocols it expects?

EDIT:
In this case, there appears to be some kind of bluetooth thingie.. so I guess you're looking for a suitable transceiver for the empeg end, and then some kind of support for whatever protocol it uses. A problem with iFruit stuff, is that it does tend towards the non-standard/proprietary/highly-profitable side of things.