It is not difficult, you can either use a cable from another bike, or make one yourself. You will need some welding skills to weld a bracket both in the frame and in the swingarm.
I plan to do it with a build -not a Honda- I've done. I've used a linkage, but when you are pressing the brake pedal, as the swingarm goes up and down, the brake tension increases and decreases. It is just a problem of geometry, but I can't do anything with it as it used to be a hidraulic rear brake -that I converted to drum- so my plan is to use a cable, so the cable tension will be independent of the swingarm movement.
