You can attach pipes into a Smeltery controller to put liquid inside a smeltery or you could use any kind of tank and attach a Smeltery faucet with a Casting table/basin on it and it should work just fine. Direwolf did this in his Smeltery build in his Forgecraft2 workshop build where he put a faucet on an ender tank.Also know how to perhaps ?
You can actually replace the faucets with TE3's fluiducts, wrench the connection on the drainage block to output mode and stick a lever nearby. Flip it on and the fluiduct will extract non-stop, flip to off to stop. I found it to be a better alternative to using the redstone clock since it is controllable, and for a full time non-stop draining fluiduct, just right click the output section with a servo and you can now set the redstone interaction to disabled so it will be active regardless of redstone signal.You can attach pipes into a Smeltery controller to put liquid inside a smeltery or you could use any kind of tank and attach a Smeltery faucet with a Casting table/basin on it and it should work just fine. Direwolf did this in his Smeltery build in his Forgecraft2 workshop build where he put a faucet on an ender tank.
EDIT: To automate it, you will need a redstone clock attached to the faucet so that it pours out liquid metals into the table/basin continuously and a pipe or a hopper under the table/basin to get ingots/blocks out and there you go! Automated Smeltery!
EDIT 2: I believe you can use this trick to put any liquid inside a smeltery. Some say you could put steam in a smeltery and then pour it in a casting basin. Too bad Railcraft doesnt add blocks of steam.