Comment 4 for bug 259878

Once you've compiled your patched alsa modules, you only need to replace snd_hda_intel.ko
You can probably get away with replacing the version under /lib/modules/$(uname -r)/ubuntu/sound/alsa-driver/pci/hda/snd_hda_intel.ko with the new version.

Once applied, you can probably get away with 'sudo alsa force-reload', however I found rebooting was safer.

You'll know that it worked if you now see a 'Front Mic' and 'Front Mic Boost' as available mixer channels.
Also, you should also see 'Headphone' as a variable output channel.