Agreed, GRBL is probably the best place to start. Forget the 3D printer software implementations - their movement planner is totally different.

I am curious, though as to why you want to use a hardware platform that is so limited in purpose. I hope it isn't cost - there are several platforms that are within the ballpark of that one that provide so much better capability and have some software support ready to go. CNC on raspberry pi comes to mind.