This guide demonstrates how you can use the Mutator class UDK offers to implement custom key bindings. I personally don't know if there is a better way to accomplish this, and I do know this isn't how you're normally supposed to use mutators. Either way, let us begin to create a custom key binding.
This guide does not cover how to create a mod, where to put files, how to compile and other similar tasks. If you do not know this information yet, please refer to different guides first (I.e. Your First Skin Mod).