Dang... Had one of those in high school, in the auto shop, of all places. They had just gotten the repair manuals for pretty much every car ever made on CD-ROM set, and had them in that, connected to an old IBM PC-AT with a light-pen touch screen display. The interface was pure MS-DOS text-mode to find the page you wanted to view, which would switch to graphics to display the page. IIRC, the CD changer came WITH the repair manual set. (Heck, the whole computer may have.)

Now the question is, is it smart internally, or does the system need to command all the disc changes? (i.e. does it mount all six discs immediately, then do the disc swapping itself based on which one you select?)