You didn't say anything about controlling a CD changer from the Empeg. That's a whole entire other can of worms, and we cover that one in the FAQ.
The only currently-useful way of interfacing a CD changer to the Empeg right now is to get one of the remote-control universal CD changer kits (or an adapter system), and connect that into the empeg's line-input. But all that would get you is the sound from the CD changer piped through the empeg, and a separate remote-control screen for the changer. Controlling the changer from the empeg screen involves a whole other layer of custom electronics and software which simply doesn't exist.
As I said in the FAQ:
"And why would you want it to control a CD changer anyway? It's meant to free you of the hassle of ever having to carry CDs around. Its capacity is orders of magnitude greater than any car CD changer.
If all you want is to listen to the occasional CD, then just get a cheap portable CD player that you can plug into its aux-in. Get the cheapest one you can, because it'll just gather dust in the glove compartment, trust me."