only thing I can tell you if your putting on the skins is to turn them inside out and put them on like a condom. Youll never get the corners right if you try and put them on like a pair of pants.
We use dry cleaner bags over the foam to help slide the covers on. (I"m talking huge honking 60's lincoln continental seats) sometimes the bucket seats are just as hard to line up but a lot easier to flip around and "masage" into shape.