Hi Bill,
from the PMC help file,
"Once a PMC module has been generated, it can then be used in the Mach4GUI. To do this, edit the screen and choose the very top screen element in the screen tree manager. Next, find the property called "PMC Objects". Clicking on the elipses button will display a list of defined PMC objects. You can choose one of more PMC objects. "
Let me know if you need any more help. I use the PMC all the time and love it.
Mike