what about wetting or lightly soaking the forward lip in a pan of water. that way it might soften up that edge a little and you can then wrap/stretch it in and around to land the screws to hold it while it dries. i realize the soaked portion will migrate back but just watch it for a couple of minutes.
it works w/ my 1 to in some cases 40+ year old gaskets for my motorcycles.
my .01 cent answer ......... what with the depressed lousy economy and all. that all i got no more.
when all is done i have painted the top so when my window gasket leaks again my stuff won't
