Well first of all, do not wear a Yankee Cap

at the presentation.
I would bring with you a qualified golfer and make him your student that you rehearsed with prior to the event.
Bring dowels for stance and plane line. Show how extensor action brings the power package to the top and shows the shoulders how to turn.
Cover all the imperatives and some common faults that students do.
You have to captivate the audience, so demonstration is key......