Maybe this applies also to the newer style dash boards, but certianly for the pre-2009 chassis, you can easily swap the single CD radio with a 6-CD one. When selecting a 6-CD radio, be sure to first take out your old 1-CD and match up the connectors before buying it's replacement. There are two differnet style radio connectors. I learned the hard way, removing my old radio after I had the replacement in-hand.
Removing the old radio should be fairly easy, though it didn't work that way for me. The way it is designed, you insert nails in those 4 holes in the face of the radio to release the two side retaining clips. Then simply pull the radio out from the dash. But I had trouble there. I ended up removing the engine cover/dog house to expose the entire back side of the radio. I then reached from behind to unclip the radio and then pull it forward.
I will report back once the new 6-CD radio is in.
I bought my 6-CD radio used, off ebay quite cheap. Just be sure to get the right one with the right connector in-back.