you have to remove the rear seat and decklid to remove them properly
here is my past experience:
Proper procedure says to remove the rear shelf cover to replcae the speakers.. I chose not to do so and it worked correctly for me, but you may experience different results
both procedures include removing the trunk liner ( black pastic piece in the rear of the trunk) - this is self explanitory for removal
If it was me, i would try option 2 and if you are not satisfied of how well teh speaker grills line up, perform option 1.
Option 1: Removing rear shelf.
Lift up on rear seat bottom and remove from vehicle. There are Several bolts at the bottom of the seat back that hold the seat in, aswell as the seatbelts, remove all these bolts.
At the top of the seats if you pull back on the seatback you will be able to see 4 black clips that hold the seat in, use a screwdriver to depress the clips and the seat should come loose.
Now you have to remove the pillar covers from the sides of the passenger comaprtment, these are just held in with b ody clips aswell, just pull on them and remove.
The rear shelf cover is next to come off. ghuess what.... more body clips. pop the body clips loose and you in business. reverse to re-assemble
Option 2: this was what i went with the SECOND time i put speakers in....
Pull up on the grills. the grills will come right out with a small bit of persuasion WARNING: you may not be able to re-install the grills very well without performaing option 1. The grills are held in by tabs that are folded over to the shelf cover. the speakers will not come out easily this way.. the cut outs in the shelf are smaller than the speaker, so a little finagleing will do the trick ( its much easier to push them out the top from the trunk )