This is what you need:
HOTSPOT2 0, 0, unID, A, 1+256 HOTSPOT2 A, 0, unID+1, A, 2 HOTSPOT2 -1, 0, unID+2, A, 3
For the base hotspot 1+256 is ok.
The moving hotspot 2 needs to be at the edited length from the base.
The reference hotspot 3 must be at the opposite direction from the base.
Here is a short tutorial about hotspots.
Library Platform, Software Engineer