The slot is better

Please tell me how to add an upgrade slot to the block crafting machine, so that the item placed there, for example, accelerates the melting speed. 

Since the addition of procedures to the "change" of the slot leads to the fact that there is a reaction when an item is removed from the slot or to an increase in the result each time the gui is opened. And in a tick, in the constant growth of the parameter when the block is updated. 

ps. it is somehow strange that there are events for changing and deleting an object .. but not for placement.