A quicker way of handling that is to change out one of the cameras in WED (or place an entity at nearly the exact location of the camera) and then pop open the WMP with a text editor. You should be able to see clearly how the entity position is identified compared to a camera. Then just run a Find/Replace Routine and reopen in WED. You should now have the appropriate entities where the cameras used to be. Assign the camera action to them (again you can do that in the text editor if you feel comfortable with it), and you are good to go.

Works well with other things too - especially if you have a lot of entities to change out for one reason or another.