gtfreak1985 just sent us this email on how to get custom soundtracks working for both GTA and ATV Offroad without having burn a cd .

I just figured out now to add your own songs to atv just like gtlc stories but it is much easier. I am listening to Korn Twisted Transister right now! You dont have to download the crappy songs form Climax! You have to convert them but it is very easy. After you convert the songs to toc( applictation for toca race driver custom soundtracks for the psp) just rename it to .at3. Here is the link to the converter there is a readme for it! You can add any song you want as long as it is an mp3. Just create the music folder from with the atv jukebox in game setup. Then pace the songs in the psp/savedata/UCUS98603MUSIC folder. then scan for my while in the jukebox menu! This program also lets you add custom songs to Grand Theft Auto Liberty Stories without having to burn a cd, then reripping it. Just rename the songs from .toc to .gta. Convert the song using the program.So if the song is FearFactory-EdgeCrusher.toc, then rename it FearFactory-EdgeCrusher.gta. I am sure this will make both atv and especailly gta soundtracks a lot better and eaiser to make. I would like credit for this as it is my first thing to find. There is a way to add custom soundtracks to any iso of any game using this program! Thanks guys!

Download the Program to do it [Here]