I'm not a professional installer, carpenter, or electrician, and I did not consult any pros. I probably use some incorrect terms, and there are probably things I could have done differently, but what I did worked for me. Be sure to take all safety precautions, and use common sense, and of course don't blame me if you screw up.
Step 1: Getting Started
Step 2: Choose Placement
Mark the locations with a piece of masking tape or a pencil. You want to place your speaker jack close to the speaker, but you need to check for studs with the stud finder. I got pretty lucky, only one was close to a stud, and I only had to move it about 1/4" over to clear it. Mark your faceplate locations with the pencil in the screw holes.
Step 3: The Scary Part
Unfortunately, I didn't take any pics of the process. But I used a combination of a 4" putty knife, a plastic gasket scraper, and the chisel to gently, GENTLY pry the molding off. If your baseboards are painted, you'll probably have a harder time, since you'll have to remove caulk, and re-caulk it (and caulk and touch up paint on nail holes, if you're picky) once the project is otherwise completed.
If they don't want to come off, DO NOT FORCE IT. It will most certainly crack. Find the stubborn nail, and use a nail set to hammer it through the board, into the wall. Label the backs of your shoe molding and baseboard, to make it easier when re-installing.
After they're removed, this is a good time to clean all the dust off, and find whatever slipped between the boards and the walls over the years. I found a penny!
Step 4: Cutting Some Holes
Double check your positioning. Double check for studs. You'll see in the pics that I wrapped masking tape around my keyhole saw, this is to prevent me from cutting too far in, and hitting the sheetrock on the other side. Cut your hole, and save the piece you cut out, in case you need to make a patch with it later, don't accidentally drop it into the wall like I did the first time.
Directly below this hole, you'll need to make another, that will eventually be behind the baseboard. There is a 2x4 that runs along the base of the wall, so you won't be able to cut your hole all the way down. I used the chisel and hammer to cut out the portion of the sheetrock that is in front of this board, so I could run the wires down beside the floorboards, so the baseboard wouldn't have to smush the wire against the wall.
**A note on using the keyhole saw. If you hit a wire, you will feel resistance. I didn't during this project, but have in the past. You'll probably also hear the wire banging against the wall if it's not in conduit, as you slide your saw in and out. If you elect to use a motorized tool, like a Dremel, to cut your drywall, you will not feel or hear this as easily. I highly recommend the keyhole saw.
Step 5: Tape Some Fish?
I bought the shortest/cheapest fish tape I could find at Lowes, I forget the length, but it was plenty long enough. If you don't have a fish tape, you could probably make this work with a weight on a string or piece of small wire, provided there are no obstructions in the wall. I had one box to install on an exterior wall that was insulated, the fish tape made it easy though.
Push the fish tape down into the wall, and pull it out the bottom. I had my wife helping me, she would look for it with the flashlight and grab it with her finger. Once or twice I had to widen the hole a bit to make it easier. Attach the speaker wire to the end of the fish tape, and pull it through.
Step 6: Wiring Things Together
Do the same process for all 4 speakers, and for your central jack.
Run the wire in its tucked area to where it'll end up, I decided to have a central jack for the 4 surround speakers to be wired to. The front center speaker will be wired directly to the receiver. Label your wires to save some hassle, and attach them to your central jack. Attach the faceplate, label it too.
Step 7: Making It Look Nice
Nail the baseboards back down. If you labelled them, you should know exactly where they go. Mine retained most of the original nails, so it was easy to line them up to the original nail holes. I also used finish nails to secure it a bit more. The nail set really comes in handy here, to keep you from marring and denting your boards.
I had a few spots I couldn't run the wire in the wall. Our living room has a wood burning stove, which sits on tile, with a large tile backsplash. I used some wire mold that has an adhesive backing. The package claims it's paintable and stainable, but I just left it white. I also had to go around the door frame of a sliding glass door. There wasn't space under the door trim, and I didn't have a router handy to form a channel in the backside of the trim, so I used more wire mold here. It's not great, but I can always go back and do a better job later (when I get a router).
Step 8: Wrap Up
Next up, I'd like to hide the power and HDMI cords. Luckily I have a power outlet below my TV, so I plan to cut a hole for a new outlet behind the TV, and wire it to the existing one below it.
For the HDMI cable, I'm going to install 2 "pass through" or "recessed media box" plates, one behind the TV and one behind the receiver area. This allows me to pass a wire through the wall, so if if want to add any components later I can use it for this as well.
update: Oops, forgot to update this with a link to the follow-up project, here.