Hello,

I do not have access to the other forums, so maybe a kind moderator could move this thread where it belongs? Thank you.

My intention was to get the Gladiator soundtrack in and get rid of one especially annoying track of the campaign map (no offense, the rest of the music is great), and with a little effort, it worked. Here's what I did:
First, get the idx extractor from Vercingetorix here: http://www.twcenter.net/downloads/db/?mod=32
place it in rome total war/data/sounds and let it extract. You probably dont need the sounds and voices, so you can delete these extracted folders.
Now theres a folder called music that contains alot mp3s - listen to these and replace the ones you want to change with your own mp3s. The name of the tracks hint when they are played in game.

The game will not use the extracted files when there's still the .dat and .idx, so move these to a different folder.

That's it! Enjoy your new epic soundtrack.

If you just want to add some tracks, it's even easier. Make a folder Music in Data/sounds and put the new mp3s in, then open the file descr_sounds_music.txt in the data folder and add your tracknames there when you want them to be played.

Have fun!