[Carver]

You can use the rotary axis as a positioning function and machine in any region in the entire model you would like. This would make the under cuts you need. You can also accomplish this by simply rotating your model and workpiece the same amount and generating typical 3 axis path limiting your machining regions to the areas requied. I do this daily and it works fine. A typical indexing head works without having to have an active fourth axis on your machine.

Good luck, Phill