Seen there was another topic here. I completely forgot! Perhaps we can merge powers and make it happen. Sorry about the inconvenience.
Not sure if there is another topic around here like this in the fan game section. But I'm currently when I get time, working on revamping the music in Mega Man X4, and perhaps hitting over the voices, though leaving Hypershell's patch with the game could work well already. (Still needs to find out how to edit just in game sound voices mostly) I can at least up the music.
I guess when releasing it though, I could just put up the sound files for you to replace in the game. I also noticed re doing the movie voices shouldn't be to hard, seeing it's all AVI format. Good video program and actors can make all the difference...
Examples of what's been done already.
Split Mushroom Stage - With boss music at the end.
2:15 boss music
X Intro stage - Music not made by me, but falls into my style.