Whose course? Some are offered by people not associated with ambulatory based organizations. Look at what is covered and who is speaking. ASPAN and some others have courses that cover a lot of the areas, but they will not go into the specifics. Their feeling is that they are trying to get people to think for themselves and rely on their experience/knowledge. Plus, I was once told that there is a test-bank of thousands of questions and they just couldn't "teach" to cover the ones that were on prior tests as they might not be the same ones that will be asked in the next version.
I took the exam and studied by reading through the book and finding the areas that I wasn't as familiar with and zeroed in on those things. Don't let the review book scare you as it is a BIG book, but it covers a lot. Plan ahead and allow yourself time to skim a chapter or two each night and when you find an area that slows you down, do a bit more digging there. The test is really about critical thinking skills and basic core knowledge. They also have a practice test for about $50 that you can take on-line and see how your test taking skills are. It also gives you a sample of how the questions will be asked.
I found the review course that ASPAN offers helpful when I was preparing to take the CPAN. It was EXPENSIVE but the handouts were fantastic. The other poster is correct though, that much of it is critical thinking. I also found ASPANs practice tests helpful. Its a bit of a rough test, and there arent as many prep materials around as there are for CCRN, but totally worth it to make yourself marketable in our area of practice.