To do that you need to come prepared. Get a list ahead of time of the organizations which will be participating and thoroughly research each organization which is of interest to you. Come dressed for an interview . Your dress is even more critical here than at a traditional interview, because of the short time span involved. Much of the impression formed of you will be visual.
Image is everything.
Bring plenty of copies of your resume with you. If you have multiple job objectives, bring multiple resumes, one for each objective. Bring copies of your top three letters of recommendation - one set for each copy of your resume which you brought. Make sure that each company you are interested in gets copies of your letters of recommendation. It will force them to file your resume differently from the rest of the stack.