Removing the soundtrack from a movie.

Hi, I love doing fan edits and pour hours into them, the one thing that stops me from doing more seriously and allowing others to see them is the way the soundtrack sounds after you have cut out shots and removed a few frames here and there. I would like to find out how to remove the soundtrack so I can add it (or another one) back after my edits are complete.
I have tried splitting the channels, but so far most of the soundtrack is still audible in channel 3 (which is where the vocals and the majority of the sound FX are in the discs I have tried).

I have watched fan edits that completely re-score the movie. How is this achived?

well taking them out and adding them is easy, just use mkvtoolnix, keeping audio sync after editing is another matter.