I have 21k miles on it. Is it hard to replace seals and oil if you have common sense for mechanical repairs?
If you get the service manual and are slightly mechanically inclined, you should be able to do it, from what I have seen.
The special tools you may need and/or want are a seal driver, some nice long hex extensions to get at your damping rod screw, a spring compressor (if you have inverted forks), an oil level gauge, and brake cleaner. At 21k miles you probably will want to replace your bushings as well, check the surface to see if they are worn.
COMPLETELY remove from the bike and disassemble the forks, and get all of the gross chitty oil out of there. Clean all of the compenents individually with brake cleaner and let them dry. Then reassemble, get those new bushings on all the way, grease your seals and drive them in, fill to the proper oil level with fresh oil, and throw the forks back on the bike.
Write down your adjuster settings (rebound, high/low speed compression damping, whatever settings your forks have, etc) when you take the forks apart because you will forget. This is assuming you have them set up properly beforehand.
Careful not to lose parts... snap rings especially are a bitch to keep track of.