Have you tried the obvious trick of overwriting whatever region you care to play with the presumably Japanese audio? Most times undubs are that simple, which when along with them containing copyrighted content means patches are a bit thin on the ground -- most patches you see will either be said copyrighted stuff or when the usually Japanese audio is hidden within the game.
That said the megaman franchise as a whole (never so much as looked at a released legends game as a hacker) has been some of the main occasions that I have seen things get very messed up coming out of Japan such that the simple replacement does not work.
Yeah I've dabbled with that demo before, the only drawback from what I played was that the cutscenes are unsubbed so you can't understand what they're saying without an outside reference unless know Japanese so I was hoping there was a more complete solution.
Afterwards I tried undubbing MML2 myself but it didn't work out; admittedly though it was my first attempt at undubbing a game so I wasn't too sure on the proper procedure