After doing the tangerine technique, i could somewhat feel that the tangerine is on the back of my head. This is not just a visualization, but an acutal feeling.
So I'm guessing that you could try putting the tips of your fingers on the back of your head and while gently pressing on it, start rubing it in a circular motion for about 5 secs or so. After doing this, you should feel as if there is a point of attention on the back of your head.
*It's best to do this while being relaxed, and make sure you dont think about ANYTHING*