Yeah, well, that is the way we dealt with 'difficult' tires back 'in the day'.
I still remember 'Old' George teaching me how to do a stirrup-stretch when I was 12 or 13 years old, or so. We raced and trained on Czech-made Barum tires (incidentally, now Tufo). I was suprised to see the amount of force he applied, resulting in a series of loud, 'snapping' sounds as the basetape threads separated. The tires went on much easier, and I never had a problem mounting the tire using his technique. Also, I never had a problem with tires adhereing or flats as a result.
Today, a lot of manufactures specifically warn against using a stirrup-stretch on their tires to avoid damaging them. Today, almost everybody recommends stretching tires by leaving them on s rim (which doesn't help getting them on a rim in the first place, which can actually be harder than getting them on a rim having glue on already, due to slippage). Though I don't advise that you do it yourself, lest you damage a tire, I have been known, on occasion, to revert to my old ways for a difficult tire (Dugast seta 27's, for instance)
Anyway, once a tire is nicely stretched-out (however you get there) you should not have any problem mounting it.