I did mine myself. You just need hog ring pliers and a bunch of hog rings. I bought a nice, heavy-duty set of hog ring pliers for when I restored my flood-totaled Caddy. Those cheesy ones that come with the covers are tough on your hands, don't have the right angle and fall apart.
There are a couple of spots where the fabric is pulled tight to the frame to give a crease. If you aren't careful the crease won't come out right (mine didn't). If I could have had the pair done professionally for $200 I'd have done gone that route. The local guy wanted $200 per seat so I just did it myself. They came out decent, but those creases bug me.
Jim