HOw do you edit music.

I was trying to mod the music for RTW. I extracted the music files with idx. Then a folder appeared called Data with the folder Sound which included Music, SFX, and Voice folders int it.
I replaced the music files with my custom mp3s and moved the music.dat file. Then i loaded RTW and it got stuck at the loading screen before the main menu.
I exited and put music.dat back but renamed it music.dat.BAK. it still didnt work. So I put music.dat back to normal (renamed it music.dat) and then RTW started to work.

So how can I load RtW with my custom music without it freezin? ~:mecry: