Ceet takes the cake on this one. They used to have a VERY comprehensive how-to section on their website. However, somebody got the bright idea to take down their fully populated HTML-based website and prop up a Flash based one that is less than 40% complete.
At any rate, YES.. .the seat cover looks like there is no way it'll fit, but it will. It will need alot of stretching, so I'd lay it out in the sun for a couple of hours before you get ready to start. You need to stretch the "pocket" at the front of the cover over the nose of the seat, and staple it once or twice under there when its centered. Then, pull it fairly tight towards the back and staple it a couple times there. Do the same with the sides near the lowest part of the seat, and then start working your way around what's left. Use staples sparingly until you've got it looking good and you're sure you won't have to remove the cover and start over.