CPlane_Change is universal command it allows you to set CPLane picker not only for labels but also for objects, another words it works like ordinary CPlane Picker. So if you use Set CPlane command you can replace it with this one, and you will have the same functionality plus ability to work with labels.
***
Also use this script (Run it once at start) and it will allow you to draw only on CPlane with snapping on objects.
script: /* Toggle projecting snaps to CPlane in ortho views */ moi.drawingAids.projectToCPlaneOrtho = !moi.drawingAids.projectToCPlaneOrtho;
By default if you draw on CPlane and snapping to objects is enabled, thing you create will be lay on snapped object not on CPlane.
This script is very handy tool to keep all curves on CPlane.