the door panels on every Saturn ive worked on comes apart by taking screws out and the fron of the door comes off to get to the inside of the door
If you have manual windows, you have to make, borrow, rent, or buy a tool for removing the crank c-clip. A stop at a local body shop might get you a free removal.
If you have removed the crank handle or you have power windows, do this:
1 - Remove your trim triangle. It's a black piece of plastic used to cover the bolts, which hold your mirrors on. Simply grasp the top of the triangle in tug. A spring clip holds it in place. Inside the cavity will be a piece of acoustic foam. Pull the foam out.
2 - look down in your inside door handle well. There should be a rubber insert, which covers two screws. It is glued in the center, allowing you to move each side away to expose one of the two screws. Remove these screws.
3 - Remove the screw below the speaker. The screw is located toward the front of the door. You can't miss it.
4 - Remove two plastic retainers, which will be located on the rear (latch side) of the door. These are typical GM two-stage plastic retaining pins. Use a screwdriver to pull out the top part of the pin. The bottom part of the pin will slide out easily.
5 - The door is now held by 5 nylon friction pins. Three pins run along the bottom of the door and two pins run along the front of the door. Start from the back (latch side) and gently pull the panel away from the sheet metal. Use a tool to help separate the door panel. It's smart to wear gloves as door panels have some sharp edges. Tug on each location where you feel resistance. The pins will pop out of their holes.
6 - While gently rocking the door panel, lift straight upto remove the top ridge from the window opening.
7 - Disconnect the wiring from the door panel.
Now you have access to the speaker and some of the window mechanism.
Note: If you can reroute the wiring for the power mirrors, the trim triangle is a great place to install a tweeter.