Why not! With the given system it should be simple enough! Right?

__on_dispenser_action(name, pos, direction, item, result_item)

• name: The name of the dispenser action
• pos: The position of the dispenser
• direction: The direction the dispenser is facing
• item: The item being dispensed
• result_item: The resulting item, that is, the item that would go back to the dispenser (if it has space at least). May be null if nothing should go back