If you have a few days, try reading parts of Lippincott Biochem. I started by reading the summary at the end of each chapter (one page). If the material sounded unfamiliar, I re-read the whole chapter. Worked for me.
I recently bought Lange Biochem flashcards and I really liked them. They break it down in very simple ways and in the beginning of each section provide a few flashcards with an overview of the system e.g. amino acid metabolism, then give you vignettes with answers about that system. They aren't that expensive either.
nbme ask bioch fundamentals? oh f.. I don't even know what that is, I thought HY material were diseases correlated with the reactions (enzyme deficiencies and stuff). I think it is worthless to study the whole lehninger just to answer one or 2 questions.
Nevertheless I'd like some feedback from someone who already did the exam.