If tickets are really going to sellout in under 5 minutes, chances are good that only the very first person in line at the box office will get anything. I've never heard of a box office allotment of tickets for the club. I wouldn't count on that. I'd say you're better off on-line.
Don't let the presale fool you. Part of it's purpose is to generate excitement for the show. Tickets for the Garbage and Interpol presales disappeared just as quickly. Then tickets were available for hours, if not days, when the real sale happened.
I'm not saying this won't be a tough ticket, but it might not be as tough as you think.