Tried this last night and it works really well so I figured I'd share it here, even though it's a few years old. It can even take advantage of your GPU to run faster. The sample song I tested with is 5:56 and it only took 30 seconds for this tool to split it into separate .wav files for vocals, guitar, piano, bass, etc. I recommend following this guide here:
https://www.reddit.com/r/musicproduction/comments/1704kob/co...