I actually have a similar question, and not sure really where to start looking...
I was thinking about buy a headunit with an IR remote, then installing an computer based IR immiter to controll the head unit, on th ePC I would run some kind of software that would replicate the functions of the head unit, includinge the display... so you could use your touchscreen to control the head unit.
So basicly, is there any software currently available that would emulate an Head units function (Am/FM(FM1 FM2 FM3),CD (track up/down) volume, freq scan, and preset ...ect!
Is there any software available that would be able to replicate/send the IR signals to the head unit.
I know to search, which is what I was doing when I came accross this