I went through this several months ago. I bought the mounts on Ebay (you have to be very careful about the mounting holes), and converted 3 leica lenses and a CV 15mm screw mount. It's quite a bit of work and a lot of it is making sure the lenses focus well before conversion. If they don't, don't bother. I printed a focus chart and took photos of it, then printed those and compared. Next I took off the original plate and measured the thickness around it in several places and noted that. then I measured the thickness of the new plate and compared them. Taping a sheet of 400 grit sandpaper to a piece of glass, I sanded the back of the plate, rotating and measuring till I got it as close as possible to the original. After cleaning, I screwed the new plate on and took new photos of the focus chart. Printed those and compared to the original. Two of the new mounting plates needed thicknessing. The third was close enough. I used black and white enamel to paint the recesses milled into the plates to code the lenses.
The screw Mount was a different story. I had to remove the adaptor several times and ended up shimming it a bit. Wasn't that important with the 15mm however, as everything is pretty much in focus, from 3' to infinity at f4.5.
In summary, it's a lot of work, but I figure I saved a good $600+. Worth it to me.