Question: single motor instead of two

[javl]

It seems this fork is meant for hector-style drawing machines that use two motors. Do you know if this grbl port can also work with a single motor (or have any suggestions for adapting the code to make it work)?

Some background info on what I'm trying to do:

I've made a device that has a linear axis (x) which is housed in a ring that can spin around (Z). So as Z spins, the X axis spins with it:

So while my carriage (the black square) can cross the center, it's effectively a single polar motor:

Currently I convert my paths to very small steps, then to polar coordinates and move the machine accordingly (so the X axis is my radius, Z is the angle (1 rotation is 360 steps)).

I'd love to be able to not need all of these small G1 segments and have the machine move in a more fluid motion between the points by just specifying the begin and and polar coordinates and have grbl calculate a straight path between them.