Important tools: a hacksaw blade, a small straight screwdriver, a small offset screwdriver, and a small hemostat (street name - "roach clip." If you have a friend who's a physician, s/he ought to be able to get one for you. It's the tool they use for sewing stitches. I believe that auto parts stores may also sell them, or something similar.)
Step 1. Bend the hacksaw blade into a hook shape, sort of an elongated "J." (Another possibility would be to use a spare dipstick, if you have one around.) The object is to create a tool that will kind of cradle the clips that hold the door waist seal in place. If you are lucky, you will be able to make something that will hold the clips tightly enough to use your new tool to seat the clips back into their positions holding the seal; I was not so fortunate, so I'll continue with my technique.
Step 2. Pull the old seal off. The clips on my car all stayed in place on the rail when I pulled the old seal off.
Step 3. Get a strong hold on the clip on a top corner with the hemostat. Slowly work the clip off of the rail with the small straight screwdriver. If you are careful, the hemostat will still be holding the clip when it's freed of the rail. Drag the clip to the opening up by the windshield and remove it. Use this process with all of the clips.
(Because of the close tolerances between the door and the window, you have to insert and remove everything up by the windshield, at the opening created by the angle of the window.)
Step 4. When you've removed all of the clips, set the new seal in place. Insert one of the clips into the hacksaw blade "hook" that you made in step 1. The blade I used was just strong enough to hold the clip securely, but weak enough to bend slightly as I was pulling the clip up onto the rail, making it easy to remove the hacksaw hook. Once the clip is started onto the rail with the hook, carefully remove the hook. You will need to keep the clip in place with one of the small screwdrivers as you wiggle the hook free.
Step 5. Once the hook is removed from the clip, use the small offset screwdriver to pull the clip up into its fully seated position. I had to push down on the seal with one hand and pull up with the offset screwdriver in the other hand to get the seal into the correct position and the clip to seat properly. With most of the clips, I had to seat both edges of the clip individually.
Once you've seated all of the clips, you're ready to repeat the procedure on the other side of the car. Soon, you'll be driving with a car with new weather-stripping!!