Once you've run one of the client modules, it stays active in the same way that PRPC does - you only need to run it once. So once you run the PoseFilter module, it sits there permanently looking for PZ2 or P2Z files being applied from P3dO. When it sees one, a box pops up that allows you to select the body parts you want the pose to apply to. Hope that helps - as I said, I haven't used the client modules much so I hope I didn't miss anything vital.