To edit a pose saved in ZBrush Pose Tools after having sent several poses from CC, follow these steps:
1) Use GoZ in ZBrush to send the last pose sent from CC back to into CC to align the link data.
2) Switch to the pose that needs to be updated in ZBrush Pose Tools.
3) Activate ZBrush Pose Tools > Edit Current Pose.
4) Use CC GoZ > Relink to update the pose.