I just rebuilt mine about a month ago, using a stock rebuild kit that I bought from Ducati of Seattle. They are still available, and dirt cheap.
The only hard part was digging out the old retaining ring for the dust boot. It goes in like a circlip, but has no holes to grab with a pair of circlip pliers. I wound up digging it out with a dental pick and a small screwdriver.
When you take it apart, make darn sure you keep the whole o-ring, piston, cup, spring, etc. assembly in the order in which it comes out. Put it aside where you can leave it that way, or take a picture or two, or something - the "instructions" that come with the rebuild kist are anything but. If you mix up the pieces on the old one, you may never figure out how to install the new one without them as a guide.