Hello, I believe that I am the first one to find this out on this website.... I'm not sure... Too lazy to look. xD.
So This is basically changing the game BGM ( the music that comes on when you're in the lobby, at the log in screen, and in a game room) to whatever music you want.
There is only 4 song's to choose so choose wisely.
1. Go to the Crossfire Folder -> rez -> BGM
2. Download your 4 songs and name them exactly the same name as the BGM files....
3. Create a backup folder and put original BGM's in...
4. Put new BGM's in...
5. Have fun and thank me..
Someone think of an Easier tutorial? PM me it and I'll consider it.