taking apart your civic's rear deck isnt extremely hard, but it isnt the easiest to put it back together to fit the way it originally did. there is an easier way of replacing the rear speakers in our civics.
the clips under the rear deck (in the trunk) can be "ripped/cut" out and the speaker can be removed through opening in the deck that the magnet of the speaker sits in. then you can mount your new speakers to the bottom of the rear deck with self-taping screws.
*note: the proper way by removing your rear panels is of coarse the correct way of installing rear speakers but the panels can sometimes rattle/squeak. also by mounting the speaker through the trunk will give the tweeter alittle more room from the grill.
personally, I installed mine the correct way but it seems that many people would rather take the latter.