I replaced mine on my first bug and they came as one piece, I just stretched them over the door and into place. I don't remember having to put any thing underneath the seals to hold them in place but I suppose you could put a bead of silicone down first if necessary. You can always reach out to the folks you buy the seals from for thier opinion on the best way to install them.
Blue Baron wrote:You will have to remove the door stop check arm pins to install the seals. A little contact cement in the seal channels wouldn't hurt.
X2 on this. Out here in the desert they dry out fast and shrink a bit but the contact cement helps keep them in place.