I've updated the wiki page with instructions for installing with the latest ALSA snapshots from Takashi Iwai.
These snapshots include the official driver update from Wei Ni of nVidia for HDMI audio. It's still not perfect, but it is cleaner than the old patch. GT220 users still need a little additional patching, but nothing too rough (3 new lines).
If you make the change, please report how it goes, either here or on the XBMC thread. Thanks!