I still have my 4040b, but you're really pushing it if you think you could make it dual layer.
its only a 4x drive, I think it was lg's first dvd drive? It was released before people ever believed dual layer would be possible.
I've been itching to replace mine, but it won't die. I think I might hold out until the new lg drive comes out with lightscribe support.
anwways, i'm 99.. hell 100 percent sure you would never be able to get dual layer support out of a 4040b.