factory cd changer to aftermarket stereo

Hi, Yesterday i did my buddies 99 Ford Expedition Eddie Bauer we put in a Sony head unit and XM radio, the car came stock with a 6 disc CD changer located in the center console, so now we're trying to figure out how to get that CD changer to work with the aftermarket stereo. I have asked shops if this is possible and i have been told No, but i still believe it is, Does anyone know of a harness or anything that might help in this situation, thanks

you might could make a controller for it if you knew exactly what input was needed to make the cd changer do something and run the audio through an aux input, but it is impossible to get it to work with an aftermarket cd player directly.