Optically, this is an amazingly easy lens to work on but there are some issues that you have to pay attention to.
First is the front lens group. It has to be screwed in to the optical barrel very tightly with a sharp spanner and then not touched again. If it gets loose, the aperture blades can skip out of their channels and then easily bend. If you bend one, you need to take the replacement from a broken lens since there are zero spare blades left at Leica or any of the suppliers (according to Sherry K.) And since each lens only has four blades, that's much fewer than most lenses and so there are even fewer spare blades available.
Second is that YES, you will have to take the rear group off then a lockring out with a spanner, in order to get to the focusing helicoid. The threads in the helicoid are VERY fine. The finest I've seen in any Leica lens. This is critical because if the shear of the lube is too high then your lens will be stiffer. Don't just oil it up either that will cause lube or whatever to migrate into the aperture and onto the inner element surfaces.
If your dust is really bad and you don't have a ventilated hood for camera work or a dust free area, it would be better to send it out for CLA, in my opinion.
Phil Forrest