Pretty easy to do... couple of screws on top under the rubber mat. Pop the two side vent/pocket parts loose. I think there's a screw under the little black panel where the 3.5MM jack is. I haven't had mine apart in a few months.
Removed my radio this morning and installed the PACFRD24 and my Kenwood sound powered amp. What a difference! Anybody thinking about putting a amp on their stock head unit this is the way to go. Plug and play. Allows the use of RCA plugs. No searching for speaker wires for speaker level inputs. Very easy install just takes a little time. Came out great and sounds 10 times better.