Contact glues generally retain their original colour when dry. Yellow, red, green - I've used drums of it over the years. There's all different sorts out there but most do the same thing - generally stick like shit to a blanket! Paint the glue on both surfaces - let air dry for a few minutes till touch dry - then press together. You only get one go!
Excess can be cleaned of with thinners (or turps will do). Won't hurt cover or base.
Paul, you can unbolt seat brackets, staple on cover (with glue too if you like) then bolt brackets back on. Just need to keep an eye on bolt tension after that. If you want to get real fussy, unbolt the brackets after they leave an impression on the vinyl ( and glue has set) and them trim exactly to bracket shape!
Still reckon you should do it all with staples (with a bit of glue to make us all feel better
)
Very nice bike!! Whats that gold donger thingy hanging over muffler?