Nothing difficult, but having the right tools makes the job easier. There are various alternatives to the special tools. You can buy or make the tools you need for less than the labor cost from most shops.
Just keep everything clean and take your time and you will be fine. Always a good idea the take pictues as you take apart.
About the only thing you could do wrong is put the seals in upside down, so pay attention there.
I am planning to do a seal and oil replacement this sunday and will be taking photos for a how-to writeup. The reason is that I blew a seal last saturday after bringing a wheelie down a bit hard. A friend has a brand new traxxion toolkit, and we're giving it a whirl. Neither of us has done this before, but we're garage monkeys so we're giving it a shot.
People typically recommend replacing the bushings while you're at it. I talked to Louie at Race Tech about bushings. The gen1 10rs have no inner bushings and 2 outer bushings. These bushings cannot be replaced separately. Kawasaki makes you buy the whole tube. The good news is that these bushings hold up incredibly well, according to Louie.
EDIT: I just looked at the how-to by garth285 linked above. Paydirt!
Hey garth285, you have an error on your fork seal replacement page. The Kawi 04-05 10r service manual stipulates that the oil should be covered with an air space of 91 + or - 2 mm as measured from the top of the OUTER tube, not from the top of the inner tube as you stated a couple of times. I discovered this error after I put the fork tubes back together and back on the bike.
Now what I plan to do is measure the height from the top of the inner tube to the top of the outer tube, h. That height (h) is the height of a cylinder of oil inside my inner tube that is missing. I know the outer circumference of the inner tube is 143 mm, and I will just assume that the tube wall is about 1 mm thick. The radius using 143 is found by 143/(2*pi) = 143/(2*3.14159) = 22.76 mm. Take 1 mm off the radius to account for the thickness of the tube wall, and then calculate the volume of the cylinder of height h: volume to add = pi*(21.76 mm)^2*h = 1487.5h mm^2. That calculation yields cubic milimeters. Divide by 1000 to get cubic centimeters (cc). 1 cc = 1 ml.
So if anyone else made this mistake, the above is a way to figure out how much missing oil to add to each fork tube without having to do anything other than open up the caps with the tubes still on the bike. I suggest using a syringe with rubber tubing.
UPDATE: on my 10r, the distance between the top of the outer tube and the top of the inner tube is 12 mm, with the cap unscrewed and the leg shoved all the way up as far as it will go. The calculation works out to be 17.85 ml of oil to add. This is not a trivial amount.