@Faber, IMHO there is no right or wrong way of doing that, here is how I do it:
-after taking apart, washing, cleaning and assambling the guidance cylinder and piston again
-I fix the shock in a vise, give the chrome piston a fine smear of fork oil, pull oilseals from top down to its seatings (no hurt of seal lips)
-take an U-shaped piece of a plastic pipe and hammer the seal into its seat
(still without oil fill)
-now I fill measured amount of fork oil
-recap with lid and snap ring