I've done it--everything including new springs; it's not easy, but I got a near perfect result--the key is patience (I spend 2 weekends each seat--the minute I got tired or frustrated, I stopped and came back fresh.
Another tip I picked up here was to use a plastic garbage back over the foams in order to get the cover on--I don't think I could have done it w/o this trick--it allowed me to fit the cover, ring it to the frame and see what it looked like--I could then easily undo the few rings and refit it until I got it right.
Personally, if you have the $$, I'd pay someone else--I did it because I always wanted to try it. And doing it yourself won't necessarily save you all that much, once you figure in the time
