you're best bet is to check out the interview feedback at studentdoctor.net.
the panel really isn't too bad, and it also depends somewhat on the questions you're given and those who you are paired with i think. but, just take it as a normal interview. i think one suggestion would be that during the "team" question (the last 10 minutes or so), make sure you are both contributing to and listening to your fellow interviewees since NU is PBL and depends on cooperation. also, when giving your answers, make sure to have eye contact not only with the person asking the question, but with the other 2 interviewees and other 2 interviewers.
good luck