I just now discovered something I thought to share!
In the app Ringtone Maker you are easily able to make mp3 notifications of any parts of your music, and it has the option to be saved as a notification into your notification collection (and successfully does so). It's quite awesome!
... Annnnd, once again, I want to say that I also found that the app called Light Flow is also awesome for assigning custom notifications to a number of apps. I don't even use the led flashes. Just custom audio and vibration notifications.