I don't know if it's been done before, but I have come to an ingenious solution to disassembling our entire rear seat to change the speakers!!!
I am going to go in and dremmel out a hole just large enough to have direct access to the rear deck speakers and I'm also working on a way so that the rear grilles will simply snap-off or lift-off the rear deck!!!
When it finally gets warm enough, I'll go to it, and trust me when I say that there will be pictures all the way through the process to keep you all up-to-date on how the modifying is coming along!!!
PS--If you have any advice for me on this project, feel free to post it up in this thread! Thanks!