Worksafe NZ have a 'Best practice guideline for working at height in New Zealand' which covers all the aspects of working at height as you mentioned. This is a downloadable PDF and can be found on the Worksafe NZ site by putting 'working at height' in the search function. Hopefully this will give you the outlines for what you are looking for. Chris Cox from NZ Safety Blackwoods Work Safe Training provides a course in Unit Standard 17600 that he delivers for managers etc.
I agree, of the 66 prosecutions to date 61 of those relate to training and competencies. I would have thought that within this there was some level of poor governance that had an influence?