EMC - M codes pause motion?

In EMC m-codes cause the interpreter to pause motion, example:

g02x30y30i30j0f300
g02x0y0i0j-30m7(or m8,m3,m4 etc.)
EMC executes 1 quadrant arc, pauses motion, turns on M code output,
resumes motion to complete arc.
If the M code is removed the motion is executed seamlessly.

I need to be able to turn outputs on/off on-the-fly, Is it possible
to setup EMC to allow M code output on-the-fly?

Thanks,
Dean