For statistics, I recommend the book "Clinical Pharmacists' Guide to Biostatistics and Literature Evaluation." The chapters themselves weren't particulary useful (They're too long, and the explanations are confusing.), but the practice questions at the end of each chapter are wonderful. Just work through the practice questions, and for the ones you got wrong (which will be a lot of them), figure out why, and study your notes frequently. The questions are difficult, especially for the later chapters, but if you can do them, you'll be fine.
For the clinical sections, I only used the ACCP prep course. Most of the time, I just took notes from the lecture (with slides), not the book chapters, although I still skimmed the book chapter and did the assessment questions to help identify significant topics that weren't covered in the lecture.
You need to know drug interactions. You should already have a solid base of knowledge in this area, but consider coming up with some mental system (mnemonics or whatever you have to do) to make sure you have all the major drug interactions down pat.
Even after going through the regulatory chapter twice and studying a considerable amount of outside materials, there were still more than a few regulatory questions on the exam I had no clue about. I don't know what to tell you.
ACCP's mock exam is considerably more difficult than the real exam. Don't panic when you feel like an idiot going through the mock exam for the first time.
