The essay format is EXACTLY the same from year to year. They will give you a statement like "Censorship is the responsibility of the government" and then they will ask you to do three things. 1) Explain what you think this statement means 2) give an example where this statement might not be true and 3) Explain what you think determines when this is and is not true.
The statements vary, but I think they're all posted on the AAMC website somewhere.
You must do all three tasks to get full credit, and the only time you're supposed to put your opinion in is task 3. Kaplan has some good sample prompts and sample essays, but I'm not sure if they're accessible online without signing up for the class. If not, go to a bookstore and glance in a Kaplan book for the format.
I didn't get the impression that the writing portion mattered a whole lot though, why else would they use J-T instead of some intelligible grading system?
I think you can write within the time constraint if you do some practice essays, and take a minute or two to outline what you want to write on some scrap paper.
Here's a really long hyperlink, but it's Kaplan's site that has some practice stuff:
http://www.kaptest.com/repository/templa...at_writing.html