During the interview process, usually after the one on one with Skovgaard (who I told is not there right now and will probably not be back) and Wakefield, they will give you 5 hours of free Frasca time to practice for the sim eval. First of all, to call it a simulator is kind of funny, but that's what you have to do. Even if you don't have any time in a Frasca, this 5 hours should be plenty of time for you to get proficient. If for some reason you need more time, they will most likely give it to you without a fuss. As for the presentation, a wealth of aviation knowledge will help, but in the end its all personality. Be able to communicate simple ideas to people so they can understand it. If you can do that, you should be golden.
Oh yeah, and for anyone who is considering doing the internship......I definitely recommend it.