I just took this exam on Wednesday and found it to be a bit more difficult, but quite doable. There's already a post under the Specific Exams section of the forum. I've posted the link below.
http://www.degreeforum.net/specific-exam...-clep.html
At the suggestion of several people on the forum, I bought "The Complete Idiot's Guide to American History". (I bought the Kindle version which was much cheaper than the book, and downloaded the Kindle for Mac software.) I found this to be a very helpful overview of the material. I also used the Peterson's test. Personally, I struggled with knowing the more contemporary writers. In general, the American Lit. exam is the A & I Lit Exam + additional knowledge of specific American authors and poets. (If you can take the A & I Lit. Exam first, that would be helpful.)
Some questions will give you a passage and ask you who wrote it. I thought these would be difficult, but, based on general information about the authors' styles in the "Idiots Guide" I could be quite certain who wrote the passage.
All in all, I studied for a week and passed with a 63, which I was quite happy with. Now, my high school did have a pretty rigorous Lit. program, and I drew from that alot. But, again, the "Idiot's Guide" covered most everything on the exam, so using that should be quite helpful.