The only article I have ever come across that discusses anything like this is the one by Alan MacRobert in Sky and Telescope, February 1996, page 76 and he discusses his experiences with a pyrex mirror that was slightly undercorrected, but responded to SEASONAL ambient temperature changes to become optimally corrected from November to March. Warping mirrors in any gross fashion to transform them from spherical to parabolic is probably very hard to do with anything other than pyrex by heating.