Actually, it's not Tool claiming that the song is sacred to folks at the Tracker School (actually just to Tom); it's Tom (or his secretary anyway) who claims it's sacred. Obviously, when I heard the early assertions that it wasn't Lipan I immediately thought of Ronald Vincent. This could still be a hoax, but if so, it's a decidedly more elaborate hoax: rather than just making up a name (and easily avoiding a SLAPP without having to do any work), they'd have convince a purported expert whose claims are already challenged to take part in the hoax, which would likely cast even greater doubt on his claims (and, since he makes his living selling Lipan wisdom, threaten his livelihood). It's also riskier, since they're not inventing a philosophy/religious practice from scratch this time, but actually connecting it to a real people with a verifiable history.

So if it's a hoax, it's a well-developed one. (As an early lachrymology and spatilomancy* skeptic I'd like to think that the band felt a need to go to greater lengths to fool their fans, but then I remember how easily the Christian conversion hoax was accomplished.) I'm sure there are other possibilities, but I only have two well-fleshed scenarios in mind: either it's a wonderfully complex hoax or it's that it's their version of Arnaldo Lerma's usenet reveal--
http://en.wikipedia.org/wiki/Arnaldo_Lerma
There seem to be a lot of parallels between Tracker School's classes and CoS's OT levels.

Either way, it's damned cool.

*"Spatilomancy" is the closest divination practice to the aenema ritual I've yet come across. An alternative would be scatology, which I think makes it clear it's a hoax as well.