When it comes to learning the cull, there is no better resource than Kostya Kimlat's DVD "The Roadrunner Cull."
The DVD is a little pricey, but it is worth it's weight in gold - you will learn an excellent cull, learn some tricks, listen to his advice, and watch Kostya perform to all these people. It's awesome. I would have gladly paid double or triple the price for the DVD.
Good luck.
-Sanj