You should be able to discern the method from reading his description. It's actually very simple. On the side of the book you tab the main chapters - Chapter 1 - Math, Chapter 2 - Thermo etc. On the top of the book, BY CHAPTER, you tab formulas or diagrams you find important. When tabbing at the top, start either at the inside of the book and work your way out or vice versa so that there's a specific pattern. For example, my first formula that I find useful I may tab the outer, right corner in chapter 1 and then work my way inward toward the spine. When you get to Chapter 2 you do the same.
It's easier if you use specific colors, for example, chapter 1 red tabs, chapter 2 yellow etc.