Hauser and I have the perfect solution but you need to be careful with your hands when you tuck the corners in as you lower the softtop in the well. Basically, one side is easy (the side you are standing on as you lower the top - just don't lower it quite all the way and you can just tuck the corner underneath the frame). The other side: after you reach the other corner, you lift the top bacck up just an inch or so, then 'do' that corner, and you're all set. Following this procedure cured my softtops corners that had been curled up for several years, after just one 'treatment' (top sitting stowed properly for a bit of time in the well).
I believe Richard Madison refined the technique, and saved his hands, by crafting out of the corners of a plastic one-gallon-milkjug some kind of 'shoe-trees' that he would put underneath the top as it went into the well. I stilll have to try this out for myself.