I actually installed this in the last boat I built which had a lot of rocker but I didn't have to open it up since the boat didn't need it after test paddles. I was going to use SS cable from boating stores used for sail boat rigging in a sleeve of polypropylene from the hardware store. It would be a push/pull skeg like commercial kayaks. When the skeg is in the down position you can release it from the box by pushing it up on an angle towards the axle. This is how most of the commercial manufacturers have it set up for repair if necessary. You would undo the lock screw on the cable on the push lever first. That's also how you would repair a cable.

The skeg drawing is a pdf file and should open up automatically for you in Acrobat reader. If it doesn't and you want it, email me.