The amount of memorization you must undertake for an exam depends on how well you remember what you've read and how well you know the software. If you're a visual thinker and can see the command line in your head, you won't need to memorize as much as someone who's less visually oriented. However, the exam will stretch your abilities to memorize product features and functions, interface details, and proper configuration, as well as how they all relate to the Cisco IOS.
At a minimum, you'll want to memorize the following types of information:
If you work your way through this book while sitting at an appropriate PIX device with the 6.x IOS installed and try to manipulate this environment's features and functions as they're discussed throughout, you should have little or no difficulty mastering this material. Also, don't forget that the Cram Sheet at the front of the book is designed to capture the material that's most important to memorize; use this to guide your studies as well.