I did it! I spent more than 10 minutes on my elliptical trainer last night - AND I FEEL FINE TODAY!!!!!
I did 5 minutes going forward at low tension and not super fast. I felt it in the muscles, but no joint pain. Did 5 minutes backwards, and apparently my hamstrings are stronger than the quads, cuz there wasn't even much muscular pain there. Switched to forward for another 5 minutes, but started to get joint pain after a minute, so I stopped. Ice for half an hour, and a couple of "cracks" when I straightened the leg, but really, it seems fine today.
On the road to variety of activities, strength of muscles, loss of weight, and more permanent repairs before my knee turns into a salvage case. YIPPEEEE.