PWM spindle control in MACH2

Hello,

I've got one of the little Homier mini mills, with variable speed
spindle control. I know Mach2 supports some sort of PWM output, but
I have no idea on what type of output it is (step/dir?), nor how to
interface it with electric motors (+/- 10V?)

I've seen that the parallel port breakout boards from
campbell/PMDX doesn't have PWM spindle feature but that something is
in the works. How have people been doing it so far? What components
are required? I'm totally lost on this. Thanks for any help.