I have been asked a number of times in the last few months where I learned to speed-read. The answer lies in the book The Four Hour Work Week by Tim Ferriss. In this book there is a small module that gives an explanation of how to read faster. Ferriss also has a blog post where he goes more in depth on the process of speed-reading. I may do a post on this book in the future... It has so many great applications!
The blog post can be found at the following link: How to read 300% faster in 20 minutes
If you have any questions on this subject I would be more than happy to help.