I'm sure there are Maoris out there who will have a good chuckle this, but I think we got it broadly right. We'll do it better next time and I think it was brave undertaking considering this has been one of the most epically miserable, wet, boggy summers on record. Here's the video summary, with text instructions below. Let me know how you get on.
Full instructions at: http://baddadgreatkid.blogspot.co.uk/2012/08/project-make-your-own-hangi-earth-oven.html
Bad Dad website: http://baddadgreatkid.blogspot.co.uk