Sure. (Thanks for asking.) It was one of the first things I learned when I started studying (self-)hypnosis. It's a simple way to have access to the unconsciousness without going into a trance.
There's really nothing to it. You induce a light trance and ask the unconscious mind to create a simple unambiguous yes-no signal. Finger motions are common. After that you can ask yourself questions and get y/n answers (or non-response, what I'm calling "mu", which indicates some issue with the phrasing or nature of the query.)
I should mention that you should be very careful about your self-model if you are experimenting with piercing the barrier between the conscious and unconscious minds. In computer terms, this signal corresponds to a kind of trans-mechanical oracle and having it available to your (metaphorical) Turing machine mind makes you into a fundamentally different kind of processor, operating by rules that may be unfamiliar.
