The repair was super simple. Just slide out the old seal and slide in the new.
The INTERESTING part was getting access to the seal at the bottom of the door. Just remove the front of the door -- unscrew eight screws around the edge. Try to pull off the door front. Finally locate two hidden screws underneath the two bottom corners. After several tries, find that the screws require a wrench to loosen. I pull off the door front, making only a few scratches, some on my hand, then try to pry up an edge of the door interior (plastic, but pretty rigid) to reach the seal end. After 20 minutes of tugging, pulling and close observation, I realize that the plastic was fastened to the main base or frame of the door via plastic "plugs"-- extensions going through the base's sheet metal and fused in place by some robotic manufacturing device. (This saves using screws to manufacture, but puts the onus on the repairer to find out that the door interior is thus permanently attached to the frame.) Holding my breath and using a sharp knife, I cut away the exposed heat-formed plugs to release the door interior. Finally the plastic interior and the frame were separated. (It worked! But I was afraid I might not be able to fix it back in place, since my resident robot was somewhere else.)
Now I pry up one side of the plastic interior to access the end of the old seal. Using needle-nose pliers, I pull it out about one fourth of the way. A nearby under-sink cabinet door protrudes just enough so I can't pull out the seal all the way. I remove the cabinet door. I pull out the seal, and find the other door is also in the way. I go to the other side of the appliance and pull out adjoining cabinet drawers, rather that remove another door. (Why didn't I think of that sooner?) I extract the seal and slide in the new one. The repair took all of thirty seconds. Accessing the D... thing has taken 45 minutes to an hour.)
I go to my box of miscellaneous used screws and find four of a size to fit into screw holes fitted over plastic lugs on the door interior panel -- obviously just for this purpose! -- which will securely hold the door interior in place. (GE COULD have used these, but they saved some assembler eight seconds per door using the fused plug.)
I reversed the process to reassemble. Tested -- no leaks. Only took about 1 1/2 hours all told.
If GE had designed the door HINGE to permit access, all this could have been done by simply opening the door and pulling out the old seal, replacing with the new one. So much for our GREAT design engineers.
My thanks to GE for providing me a series of challenges without any help from their documents. I did get some preliminary help from YouTube, though. This probably saved me $200 for a 60-second fix.