i cold set my kids 1983 trek tx series frame which was meant for 120mm 5/6 sp. hubs so it would fit a 135mm hub (hey, we had a nice set of 36H wheels built on Deore hubs with MA40 rims and doublebutted DT spokes, were way too nice to waste). thats about as extreme as it gets, the long thin stays on that frame were visibly curved afterwards. I aligned the dropouts by eye using a mondo big crescent wrench, then brought it into a LBS who had the fancy Park frame alignment tool which showed it to be close enough for jazz.

I used the 2x4 on the floor and string alignment method pretty much straight off sheldon's webpile.