Do an outline and memorize the shit out of it. Also, do some hypos. Consider yourself lucky to have a closed book exams. They're notoriously easier than open book exams. I've found my closed book exams to be a lot more obvious. With open book exams, I felt the need to literally write my entire outline out.
Agreed. If you know the material well you shouldn't have to look at your outline anyways during an exam, and the closed book exam will likely not be quite as difficult. For Ks I had closed-book last semester, I had a 10 page outline I memorized using flash cards, practiced hypos I could find and read through a commercial outline thoroughly, it worked well.