Thought on Adhesive:
I don't know if it would have worked for this particular application (you mentioned that the gasket was holding the inner panel of the door in place), but something I've used with success on tricky adhesive situations is automotive emblem tape, available at auto parts stores. It's a double-sided black foam tape, but with a much more powerful adhesive than the usual double-sided tape stickum (after all, it's meant to hold car trim on in summer heat, winter ice and snow, etc.). There's no real curing or drying time- once you stick it, it's set.
The major advantage it has for me is that it can be removed fairly easily when it (or whatever it's holding in place) reaches the end of its service life. A little WD-40 and a plastic scraper gets it. It's expensive, but it has saved my noogies more times than I care to tell you. Anyway, I thought I'd share that with you, in case it might make for an easier job another time.