I use the same thing on my Duke XC that my buddy Jim uses on his SID, good old Tri-Flow from a 6 oz. drip bottle. I position the bike so the fork is completely vertical, apply a few drops, and wait for it to distribute itself around the seal. After compressing the shock a few times to work some of it in, I wipe of the excess.
When the shock was new, I had to do this before every ride. The shock would "chirp" on the bigger hits when I didn't. Now that it's a year old, it only needs the stanchions lubed every second or third ride.