I've tested this method with "The Witcher 2" (NOT enhanced edition)
2xDVD9 to 4xDVD4 or maybe less if you remove, non english language.
seems to be working flawless.
I will be making a tutorial if no one do it before me.
Edit:
Tutorial for "The Witcher 2" (NOT enhanced edition)
http://fileforums.com/showthread.php?t=94213