I've found the only successful way to pressurise them is...
1. lift front of bike so front wheel is off the ground (i.e. forks fully extended, with no wieight on them)
2. (having been a racing cyclist in the past, i have a very useful stirup pump with a half decent guage on it) pump up the forks to required pressure .....anything over 12lb will make them solid, as as mentioned in a previous thread....bu55er up the seals.....I use something between 4 and 8 lb
3. As in 1. above, with front of bike supported use use preferred grade of oil (I use 10 or 15)...fill up to 120mm from top of fork leg.....I use a cardboard 'taper'
But....as said before......the difference is pretty marginal....and if you want to keep the pressure pretty constant, you will need to do this once a fortnight probably
pip pip