This technique seems to be a mash-up of early psychedelic theory and aversive stimulus therapy. At the time (1962), psychedelics were being held out as an avenue of change for some of the more deeply rooted personality disorders. One of Timothy Leary's most enduring legacy is the Concord Prison Project, where ten prisoners were given psilocybin with an elaborate followup, with surprising results: only three prisoners ever returned to prison, compared with the seven or more predicted by their warders. As an aversive stimulus psychedelics would be an odd choice: psychedelic drugs are noted for producing subjective symptoms similar to dying (which in itself isn't unpleasant), as well as the ego-death itself, the main avenue of personality change. They're also noted for producing nausea and vomiting, but aren't as good as emetics as, perhaps, apomorphine.

That said, it's interesting to note that Little Alex is no stranger to psychedelic experience, although not in a positive way: "synthemesc" is listed as one of the flavors of milkplus -- he intitially scorns synthemesc drinkers as weak, but later takes some himself (it makes him depressed).

Now, I'm interested in waterboarding: If someone who'd already 'died' psychedelically, had been waterboarded, would they fight for life, or simply give up to the feeling?