Attaching New Vinyl Material to Bucket Seat Back

The new seat covers that I purchased from Legendary for my bucket seats on my 69 Dart also included pre-cut material to attach to the bucket seat backs. The seat backs I am using are not the original cardboard style but a composite, almost hard plastic material. I originally tried attaching the new seat back material with Permatex spray and that ended up being a mistake. The stuff never dried and it did not really keep the material pulled tight. I am wondering what would be the best type of adhesive to attach the vinyl (I think that is what it is) material to the seat backs? Would also appreciate any advice on how to keep the material pulled tight until the adhesive dries? Thanks.