To use Palm's Ir with the RioCar unit, you need to hold Palm pretty close to it. That would beat the whole purpose of PalmEmpeg which is controlling RioCar when it's not visible (under the seat, in the trunk,...).
Modifying PalmEmpeg to use Ir is very easy, the problem is going to be having RioCar feed data through it's Ir. I would say some kernel modification would be required.