Here are some photos of the lifting rudder mod I made to my 19. The original short rudders are retained, and they can be raised and lowered using a 6mm line. The pull-down part of the line runs down the inside of the rudder tubes.
See the notes on the individual photos (click a photo title to display it in a page complete with text - clicking a photo image pops up a slide-show but you don't see the descriptions).
The photos don't show the actual process of threading the lines down the tubes. This takes a bit of fiddling as there are a couple of cross bars in the tubes, one partway down and one near the bottom. Do it while the arm is removed from the top, and try to get the line to go in front of the bottom cross bar. This will reduce any tendency to chafe on the bottom edge of the tube.