:h
Dunno what impression you received from the book you just read, but that's hardly a restricted (or even hard to find) area. It's managed by the U.S. Park Service, by agreement with the Tribe. Certainly one must act with the same respect as when visiting any other such preserved lands, but aside from the usual rules of conduct there aren't any special customs or restrictions governing your access to them.
Some information available here.
If you want some sort of conversation with the Tribe itself as to what if any ceremonial rites they'd like to see observed I suggest that contact them here.
Link to Tribe's Website