I've never done it myself, but I would imagine you'd have to take the dash apart, pull out the radio, disconnect the multi-pin connector, pull it thru from underneath the dash. Likewise disconnect the other end of the cord from the CD changer. Then unscrew the mounting screws in the console and lift the changer out.
Figure you gotta take the dash out anyway to connect the ipod connector anyway, right?
BTW, what are your plans for the changer? If the price is right, I'd consider buying it off you.