1. use multi-media install to remove uniaud
2. reboot
3. use multi-media install to install usbaudio files
4. reboot again
System sounds sound distorted. Actually that may be understating it. If you are familiar with waveform generators, you may be able to recognize distorted system sounds. Otherwise, you hear "sput".
added bonus, USB ports are on the back and front, so now my wiring is more orderly.