Nvm I figured it out.
Turns out tk2dUIItemEditor is overwriting OnInspectorGUI so we had to add it there.
We also wanted it so that we could make our SendMessage include an int, so we had to do some extra scripting in UIItem so that if it was default 0 it would continue with just the string, otherwise it would send the int value we want.
We also had to go into MethodBindingHelper so that functions with both 0 and 1 parameter would show up. Not the greatest work around in the world, but hey it works and now we can use it the way we want!