Well my experience is with industrial robots rather than those for CD changing but I guess the principle is the same. You obviously need to write code to write a single CD.
You then need an interface to the robot, you have two options here, either the interface provides full control of the robot, ie positioning, io control etc, or the robot has its own controller (PLC or motion controller) and the interface signals the robot to "start" and when the robot has done its thing the robot signals it is done through the same interface. How the interface will work is dependant on that provided by the manufacturers of the robot (or plc or motion controller). In my experience this would generally be via a serial port though IO cards, ethernet and USB are possibilities.
You would then have this code in some loop structure which repeated until all cds were done.