I remember an image of a tangerine or mandarine and touch the top back part of my head. That way I don't have to keep seeing the image but get a feel for it.
Rotating the eyes 20 degrees above the horizontal is enough. This removes you from trying to see with your physical eyes and helps you to 'see' with your mind. Images you created in your mind are best described as looking through a dirty window you're trying to recognise the shapes. (good trick to try if you have trouble image streaming folks).
Yes it really works. It is known that when you stop trying to 'see' with hard focus your brainwaves slow down from the beta level. By rotating the eyes up slightly (a relaxing postion) it triggers Alpha waves to come in faster.
If you ever get stuck in an exam and need to trigger your mind to respond for an answer keep your head straight and then turn your eyes up toward the ceiling gently it shouldn't hurt and isn't really noticable. It might cause you to want to close your eyes and yes it helps with 'thinking'.
Good way to try it out... imagine that you're looking at the author of the book you're intending to activate. They are sitting in front of you and have invited you to ask them a questions... now you need to think of one... you look above their head without changing the position of your head. You'll find yourself forming questions and you could hear feel or sense the author telling you to 'look in that part of the book'.
Just remember 20 degrees is roughly enough could be a bit more. No need to push it to discomfort it should be a comfortable relaxing feeling that if you were to hold it for a while with your eyes open it causes you to want to close them. That I would say is a good sign that you're now firing off alpha brainwave and are already a good way into the Accelerative Learning State.
Alex