I have an auto set up as well.
You place the iron block into a barrel. The pnematic tube takes it to a deployer and places it into the wrath furance. Turned to dark iron and then a block breaker harvests it and its brought back up into the barrel beside the one you placed the iron block in. You don't have to do anything
What you need is a wrath ignitor and a block of iron. You place the block of iron down then right click it with the wrath ignightor in your hand and it sets the iron alight (and everything else close by. I turned a whole desert into a glass covered desert).
If your lucky you make a 5 sided enclosure and right click your wrath ignighter onto the back nether brick which sets it alight, then you place the iron block in front of it and it burns the block. Then you pick the new dark iron block and hope it comes forward and not back into the wrath fire.