The major problem I had was that I didn't have the proper tools to open the lens from the front. In particular, you need a friction disk to remove a ring in order to reach the front lens element. I had seen some people use double sided tape and use the back lens cover to unscrew the ring. But the most clever tip came from Michael Freeman, a canadian lens repairer who helped me out a lot (thanks Michael!). He suggested using a 1-3/4 inch (45mm) rubber sink stopper.
I went down to my local hardware hoping to find that. But they only had smaller diameters. I had to improvise another solution from what I could find there: using a big washer that I would cut to the right size. Then I needed to use a correctly sized glass that I could invert and apply pressure on the washer which in turn would make the ring turn (don‘t forget "Right You Tight it, Left You Loose it").
Here are my improvised tools (click on images for bigger versions):
Once I got that front ring off (which is threaded), it was just a matter of getting the 6 screws off and pulling the front elements out of the lens. You can then see the aperture blades underneath. I didn't go further; only blew some air in there to get the dust off. The front 2 elements also had dust stuck in between them, so I had to get them separated. There was a slight point of glue on the second element which I removed with some acetone (nail polish). Then you can unscrew the 2 elements and clean them. Reassemble exactly the same way backwards.
A schematic of the optics:
Cleaning the optical elements is easy once you have the right tool to open that ring! I hope these instructions can be helpful to somebody.
And just to show how great this little pancake lens is, check out a some pictures. When you nail the focus, sharpness is excellent for portraiture, as you don't need to have a needle sharp lens for portraits. These shots were taken at f/1.8. If you don't mind manual focus, then this lens is really worth it!
Pictures straight out of the Fuji X-Pro1 camera, shot in JPG. Look at that bokeh!