There isn't a soundtrack, but I have a list of all the songs in it. I've downloaded most of them, but there are a few that I have not heard yet, so I don't know where in the movie they are.
1. 'Trepanning' by Headrillaz. ???
2. '5' by UltraSpank. When Barney first meets Mazzo, this music is playing in his room.
3. 'Coming Down' by Vitro. This is when Barney is in the junkyard and throws a rock at a liquor bottle.
4. 'Weight of the World' by Alana Davis. When Barney goes to find his mom with Cassie.
5. 'Mr. Jade' by Pete Droge. ???
6. 'Porcupine' by Joseph Arthur. When Barney is building the car, and Mazzo is taken for treatment.
7. 'She Cries Your Name' by Willian Orbit. This is when Barney is leaving the clynic. He's walking down the hallway, and writing his name on the wall.
8. 'Truthfully' by Lisa Loeb. The very end when Cassie visits Barney in the new place.
Sorry I didn't respond back when you posted this (I had been busy looking for it too!). I hope you get this!