I just took the Biology CLEP today. I studied for 2 1/2 weeks and got a 69! The only Biology background I have was one course in high school, and an environmental science course I took this fall in college. I used IC and I watched some lectures from this website.
UC Berkeley Webcasts | Video and Podcasts: Bio 1B
The lectures are pretty in-depth but they did help me understand some concepts that I didn't fully understand from IC. I only watched a few of them. Just the topics I felt that I needed help with.
I also took one of the free Peterson's tests online. I didn't feel like that helped me a whole lot. It just freaked me out cause it made me feel like I didn't know anything even though I'd been studying a lot!
Otherwise, I didn't use any other resources. The topics that I think are important are meiosis and mitosis (know the orders of the phases, and what happens in each one), the order of classification (Kingdom, Phylum...), the main characteristics of organisms in each Kingdom, what happens in photosynthesis, the life cycle of plants, and the basics of genetics.
Most importantly...DON'T STRESS OUT!!! I was sure I was going to fail this test, and I ended up doing fine. 115 questions in 90 minutes. I got through the questions and still had 27 minutes left, but I am a pretty fast test-taker.
Good luck!! Let me know if you have any other questions.