There are two ways to do this. I am not sure which one is best.
If you implement your own convention you can do that. Instead of returning the view : string return InputBuilders\String .
If you do this you will need to implement all of the views and the embeded views from MvcContrib will not be located.
Another way to do this would be to add a view engine that specificies that new location. Insert that view engine infront of the existing InputBuilder view engine.