Here's a link to my DIY seat cover photo essay in the R65 Coppermine Gallery.
http://www.suraklyn.com/r65_forum_gallery/thumbnails.php?album=24Yes, rivets and short metal strip secure the seat cover to the seat pan. A little dab of a quality upholstery adhesive is helpgul at the tight fold near the front corner. There are also a couple short sheet metal screws under there, too.
The rivets are drilled out and the holes, if not buggered, can be reused with the metal strip. A pop rivet tool and an assortment of rivets will be required.
The foam must be bonded to the seat pan. Some trimming may be necessary.
Fitting the cover requires quite a bit of "pull" to stretch the fabric and compress the foam. A hair dryer or heat gun -used judiciously- is quite helpful. I have seen DIY seats that were not stretched down properly and they are sad looking.
If you have additional questions and/or concerns, why not contact the seller?
Monte