While not referencing anything Native, A Course In Miracles presents itself to be a channeling of Jesus, (although never mentioned by name, most practitioners believe it to to be a message from that mythical being).
Since the early 70's it has been offered to the world as having been channeled by Helen Schuchman and 'scribed' by William Thetford. What is not told is that this book was created at Stanford University, a known affiliate of the CIA. Thetford himself worked for the CIA before teaching there, and the legend is that Helen began to hear a voice telling her to take notes and when she told Thetford about it, he said let's do it.
Thetford had worked on Project Artichoke, a part of the MKUltra program, and one of Artichokes stated goals was to create a way to make people hear 'the voice of God'. Quite a stretch to think it coincidence that he just happened to meet a woman who was hearing a voice telling her to write a book that 'corrects mistakes people have made in interpretation of Biblical teaching.' It is worded differently as I remember, but that is the gist of the introduction.
Since many native people have been taught to believe the Jesus story, it is no great leap to buy into this. There is no formal outreach, and the main organization seems to make it's money selling it's 3 volume text of Schuchman's channelings and assorted extras, and through video 'events'.
It is mostly learned about through word of mouth, with small study groups all over the world. I would say that it falls into the 'mostly harmless' category, (probably less harmful than formal religion), but with the CIA fingerprints I would say it will bring it's followers no great good. Like Scientology, it probably began as a social experiment and gained it's own life from there. In any case, it is meaningless, although it's followers will sigh and moan as they read each garbled 'verse' to each other.