Here is the best pics to describe what I am talking about.
If you press down on the top with force, don't be scared you will not break anything. And hell if you do just go test drive another X and take what ever you break. Anyway, on to the removal of the rear speaker grill. When you press down you will see that there is just a rolled tab that pops out and that is all there is to removing the grill.
There is the rolled tab I told you about:
That is how it is pensioned in the pannel:
That is what the top looks like:
This is what the bottom looks like, the tab is flat and not rolled over like the top:
The flat tab should be on the bottom for reinstall:
Then just swing it back up and press down and in to the pannel:
That is all there is to accessing the rear speaker location so that you do not have to take out the entire rear pannels.