There's a relatively simple way to give redstone pulses to the faucet, by using a JABBA barrel with a redstone upgrade. That requires 10 redstone though (which you can find in witch circle buildings pre-nether, there's a dispenser with cool loot in the middle).
You make two barrels with hopper upgrades and facades, and one of them emits a redstone pulse when empty. Then you put an item into one of them, and they pass that item into each other. The one with the redstone upgrade also emits a pulse when it loses the item, and triggers the smeltery faucet:
That is a neat way to do this. I keep forgetting about the redstone upgrade for barrels.