To make the process easy get some decent quality foil tape and a drill with a square drive or whatever it uses.
Pull off all the vents and the AC cover. Bring shop towels and some type of cleaner.
The guy above just posted and i agree. My vents were not sealed all all. Not cool to think of all the insulation fibers that would be mixed around into the air. I hate that stuff.
I left my vent covers off. For a couple seasons i would stick a fan on there to blow/suck air. Works pretty good to help the system flow.
Big thing for me is i yank the stock filter and put a residential filter there. A big 20x30. Another place where foil tape rocks. Holds better than painters tape and it also peels off cleaner.