Just sit quietly on a bench outside with your tablet, or a pen and writing pad, studiously watching people walk by (but not too intently), and making notes and sketches. The Guy Fawkes mask will freak out any JWS who know about the Anonymous declarations against the b'Org, and no one will recognize you. Carry no suspicious bags, etc., so you would appear (to normal people) to be some kind of mime. : P
Alternatively, if you wish to demonstrate and make an anti-JW statement, carry a simple sign or wear a sandwich-board, and walk up and down - across the street from the convention's entrance; ie, there's no way you are 'disturbing' them. The sign could say, for example, JWFACTS.COM :D
pepperheart - they weren't out when I went to the library last week, but next time I see them, you have inspired me. I will take some lit for the recycle bin! mwah hahaha xx