I have a Sony 10 Disc changer that is mounted in the storage area behind the back pasenger seat on the drivers side. I'm not that mechanicaly minded so I had it installed. There is a small unit a little bigger than a deck of cards that is mounted under the radio. My wired controler is mounted with velcro on the center console. I have a 2001 ST with the am/fm radio with a single cd.
Way back when my family had a '96 Explorer, we installed a 12-disc in the center console. It was handy, there to change discs, but out of sight at the same time. It did take away almost all use of the console to store stuff, but a minor drawback if you ask me.
I have mine mounted in the same place as Darrel's. Mine is a Ford factory 6 disc so it wired directly into my am/fm/cassette/cd player and lets me use the "DJ" function to operate it.