Repost from cinorhc/Kaitek:
VoodooHDA is an open source audio driver for devices compliant with the Intel High Definition Audio (HDA) specification, based primarily on code from the FreeBSD hdac driver. It is intended as an Intel-only replacement for AppleHDA on Mac OS X with support for a wide range of audio controllers and codecs.
My apologies to those who have been waiting for these sources to get released, but real life has been busy lately and unfortunately I haven't had nor will I have much time to devote to this project. I am releasing the source code for VoodooHDA, which I have been using for the past few months with no major problems or stability issues. There is, however, no official binary release at this time due to my inability to maintain and support such a release.
If there are any developers out there interested in joining or adopting this project, please email me (this username at gmail) and I will add you as a member to the Google Code project. For the time being, if you are interested in testing the driver you must check out and compile it yourself - for instructions go to the project site listed above and click on the "Source" tab. Be sure to read through Readme.txt for an overview of the state of the driver.
To use this driver you will need to copy it to /System/Library/Extensions and set the correct permissions =)
(kext helper works well for this =)