Replacing radio songs
From Nexus Wiki
This method allows you to replace the in game radio songs with any mp3 file.
1. Go into /fallout new vegas/data/sounds/songs/radionv
2. You will see a list of 48 mp3 songs that make up the normal radio station playlist
3. select your own 48 songs and rename them the same name as the game's songs
4. replace the songs in the radionv folder with your own identically named ones (you can make a copy of the original songs if you feel the need)
5. when you play the game turn on the radio to either station and enjoy!