While some people may have had success with the methods outlined above, they seem to me to be indicative of a way of acting or being that puts you at a distinct disadvantage. That is, it makes you appear to “want” or “need” or even “hope for” this job. I think that’s the wrong attitude to take into an interview, psychologically speaking.
I believe that you should show up late (carrying a golf bag instead of a briefcase), in casual clothing (something to match the golf bag would be a nice touch – ask the receptionist “Are cleats okay to wear in the clubhouse office?”) and consult your watch from time to time (shake your wrist, tap the watch face and frown as you do); let these bozos know you’ve got places to go and things to do, baby; you’re here at the interview solely as a favor to them! They may need reminding. Frequently.
I wouldn’t put my feet up on the desk (not while wearing cleats, but if you take them off it should be okay), but grab an empty chair (from a nearby office if necessary) and use that as a footrest instead, if you keep your shoes on. If you’re drinking, then by all means offer the interviewer a shot or a swig from your hip flask.
Be sure to cut the interview short as a final reminder that your time is valuable, and you’ve spent quite enough of it here. “Nice to see ya’, take care, b-bye now.”
But to answer the question directly and so that I don’t get modded right off here it wouldn’t hurt to take some printed and secure .PDF copies of your work on a CD (so that details can’t be gleaned that aren’t apparent, but may be in spreadsheet file copies, for example), and pass them around liberally. And be sure to mention your golf handicap. Modern firms are very big on hiring the handicapped, the lower, the better.