From the applicable state website:
"The Oregon Jurisprudence Examination is an open book, multiple-choice examination with a time limit of 2 hours. Copies of the Statutes ORS 675.010-150; Oregon Administrative Rules Chapter 858; APA Ethical Principles of Psychologists and Code of Conduct, 2002, and, the Statutes Pertaining to the Practice of Psychology, are provided to candidates at the examination and turned in with all test materials after completion of the exam, or after the time limit has expired, whichever occurs first."
I would prepare by getting hold of copies of the referenced documents (all should be available online). I studied for the two jurisprudence exams I took by spending a few hours each day in the week before the test reviewing and taking notes on the materials, establishing mnemonics were applicable, and just plain rote memorizing other stuff. It shouldn't be too much material to cram into your head. Most questions were pretty straightforward, and even the potentially more convoluted ethics and scenario based ones weren't too difficult. Trickiest ones were along the lines or "what state employee hears appeals regarding ethical complaint" type of questions, but there were only a few of those.