[mgatepi]

You can scan the surfaces without a reference model, but you must go in by hand(via CAD) and fix the areas that are bad. Once this is done you can then use the model to create a tool path for re-cutting. What you want to do is skip the hand part completely, and to do this you must have a solid model (perfect) of the desired shape.
What you want to do is achievable but its definitely next level.....get the right group of nerds on it and you may have something!