Possible to use external graphics program to design KiCad edge cuts?
So after further search I came across a two+ step solution. It involves importing a monochrome image using Bitmap2Component within kicad and saving it in a mod file following this tutorial then to get correct dimensions run the mod file through the online KiCad Bitmap2Component Scaler.

note that the scaler utility allows you to choose the kicad layer it saves to so you shouldn't need to edit the layer by hand as suggested in the first link.

It's a bit of a kludge but hopefully it gets the job done for others.