Skeetendo

There probably is no such tool out there (although I may be wrong), but hey, why don't you take a little time into learning how to edit the assembly code as itself ? Machine language isn't really more difficult to understand than any other programming language. What makes it difficult though is using it efficiently.

There are some explanations mistakes here and there but the overall idea should come clear by watching this video of mine:
http://www.youtube.com/watch?v=HCOqFTrLRgY