there are some advances going on joining up GH and rhinocam. i myself am very interested in this. maybe you are also interested. see link below for a simple example.
i will post some stuff later this week. that project kind of mimics your approach using rhino "dummy tools" to evaluate "millabiliy". http://wiki.mcneel.com/rhino/milltoolstoolbar
the definition will help baking the rhinocam tool catalog into rhino geometry on named layers. it work by reading the rhinocam tool catalog .csv file. i let you know.