Would not work. All you get out of Mach3 is step and direction signals. No direct servo control. The only device right now is the smooth stepper from warp9 which is comparable. It's a proprietary solution and still in beta. Works well however and I could not use my large machine without it as Mach3, depending on MS windows, is struggling to create something resembling a smooth pulse sequence.
Cheers
Rainer