Prometheus Rising. But look for a new cover for the Hilaritas Press edition.
"Here’s 4 Classic Reality Hacks From Robert Anton Wilson" is a piece at Ultraculture that I apparently missed when it came out, so I'm pointing to it now. The article, by Andrei Burke, highlights "four classic techniques for consciousness change taken from Wilson’s classic Prometheus Rising," and they seem well-chosen to me. If the article interests you, I suggest waiting to obtain the new edition of Prometheus Rising, due out soon from Hilaritas Press.