1) Remove screw (1) on plastic door handle. The push the handle forward as far as possible and pull out. It should remove without very much force. Release the small plastic piece that retains the handle to the long metal rod. It will snap easily, so be careful. Then remove the handle.
2) Remove screws (2) from armrest.
3) Remove the small sail panel (next to rear view mirror). It will pop out.
4) Remove door panel. Gently pry the plastic fasteners out around the perimeter of the panel with a large flat screwdriver or removal tool. Lift up on the entire panel so the trim will slide out of the door seal.
5) You will see an odd shaped plastic mount for the OEM 4" speaker. It's depth is only 1.75".
It is possible to use a larger speaker size, but not without considerable effort. I mounted a 6.5" speaker with a 2.8" depth, but had to make the cutout larger, build a custom mount, and modify the door panel.
No screw. There's a metal piece shaped like a U with a pinch in the middle that holds it on. You need a thin piece of cloth to slide under the window lever. Slide the cloth under the lever and towards yourself with the lever facing away (or towards you, can't remember). Try both ways. That little metal piece will pop off, then you can pull the lever off.