I've written up a little guide, on how to use ddclient (patched) to update AAAA host entries on HE DDNS:
http://blog.belodedenko.me/2013/07/dynamic-ipv6-updates-using-ddclient-for.html
I couldn't find much info on it and since it took me a while to get it working, I thought I'd share everyone else the pain :)
-- ab1