I have actually been using MoI for this very purpose recently.

I do have a program for V-Carving, aka Centre Line Machining, but for the mould I'm making it's not quite the right tool for the job.

MoI made it about as easy as is possible although it's still turned out to be something of an awkward task because of the fairly complex geometry.

The way I found to create V-Carve(ish) style toolpaths involves Sweeping an angled line (45 deg cutter in my case) around the shape so that intersecting surfaces are produced. When these surfaces are Trimmed with each other, the trim lines are extracted and used as the cutting path for the milling tool to follow.

In the attached file, I've imported some of the toolpaths that were generated by my V-Carving program, along with the characters they are derived from. The sample letter "F" has some Sweep surfaces around it, so it's possible to compare with proper V-Carving.

PS. Turn off Edges in my attached file to better see the comparison.
 

Martin.