Halftone Software for Mac?

Has anyone done any halftone images with the Nomad or Shaepoko?. I’ve found a couple of apps for PC but not for Mac.
I know how to convert an image into a halftone and then into vector art. Trying to figure out how to generate paths where a Vbit cutter uses different depths to achieve varying line widths or different size dots.

The cross-platform option would be http://www.shapeoko.com/wiki/index.php/F-Engrave

I will admit that the best option I’ve found for it is to make a custom character in a font, then set that character in F-engrave.