I've made seveal kayaks with rudders using my home made foot brace steering system. built basically like my standard wooden foot braces, See Nick's book, I make the foot peddle portion rotate to control the rudder.

You kinda have to use your imagination from the picture of the standard footbrace from my web site. the track runs along the keel, between your legs in the cockpit. your feet rest on the foot braces, like a gas-peddle. now imagine the peddles rotate when you step on the gas. I attach each steering cable from the rudder through a hole by the toe, pass it around the pivot rod then attatch it firmly to the front bulkhead. The foot braces may then be adjusted while you are in the boat with out changing the rudder settings.