I think I remember reading that the best way to activate it is by chapter.
Don't forget to mindmap. MindMapping works GREAT with textbooks. Use colors, it helps a lot. Then tack (or FunTac) it to your wall so you see it at night before bed.
Helped me a lot.
Also, I changed my mind on a previous comment. I think Philosophy books are easier to activate than novels. I just did a bunch of Photoreading for philosophy, and it wasn't as hard as the novels I'm doing.
-Ramon http://www.razor.ramon.com