Although you can re-use panel clips, it is best to plan for replacing them, BTW they are very cheap. The ones in the side panels are held to the panel by slots and do not release without a fight, which can damage the panel. I just cut the clips with a pocket saw to avoid damaging the panels. Clips are cheap and can be found at any auto parts store, panels are not. Once you remove the panel, and toss out the old clips, you just slide the heads of the new clips into the slots throughout the entire panel, line up the panel with the holes and start pressing it into place.
Yes you will need to remove the seat belts, and the "suit case" like handles above each door, and fold the seats out of your way before you start pulling. You will find velcro near the wheel well on the passenger side. Start from the hatch area and work forward. You don't need to remove the entire panel, just open it up enough to get to the speakers. Sure I took mine off out of curiosity, but it was not necessary.
Rear speakers are held in by 4 philips head screws. They use the standard GM white plastic speaker wire harness, which can be removed by carefully inserting a small flathead screw driver to release the clasps from the crimp points. Now the wires can attach directly to the aftermarket speakers. Hope this helps![]()