I think the best way to do this would be to package the Armor::onUnMount(%this,%player,%obj,%a,%b,%c,%d,%e,%f).
This function gets triggered when an Armor (%player) unmounts of a vehicle (%obj).
If you want something to happen when the player unmounts a specific vehicle, be sure to check the ID of the vehicle with the id of the datablock of the vehicle (%obj.getDataBlock().getId() == dataBlockName.getId()).
Don't forget to parent when you package an already existing function!