I was contemplating this; as the units can be had fairly cheap here in Germany. However from my extensive searching, it appeared the answer was no, unless you wanted to cut a cable and make sure the wires were to the correct pins in the Kenwood format. I don't believe there is a cable adapter that will help :(
Best is to bite the bullet, lose the CD Changer, or see if a Kenwood one would fit under the armrest.
Sorry it's not better news.
I was adament that if I have the CD changer I wouldn't want to lose it, despite the options and connectivity the Kenwood unit offers; I guess I'm a bit stubborn like that!