My friend Larry Kuznar teaches in the Anthropology Department at Indiana-Purdue Fort Wayne - he and I have been discussing torture for a few months now, and he sends me references from the anthropology literature. He encouraged me to do a cross-cultural comparison of torture - which I'd LOVE to get into, but I'm swamped right now with what I've already taken on. It's a great idea, though, and someone should run with it.
Anyway, here's one of the references that Larry suggested. There are a couple of others, but I can't find the email that lists them... sigh. I'll get them up as soon as he kindly re-sends them.
Knowles, Nathaniel (communicated by Clark Wissler) 1940 "The Torture of Captives by the Indians of Eastern North America." Proceedings of the American Philosophical Society 82(2):151-225.