Set a goal that your team will have a certain number of contestants signed up prior to each event. Check out this kewl example here. Make up a sales pitch for each of your employees. Encourage several employees to create their own bikini costumes to assist in promoting the event. Consider radio stations, clothing stores, travel agencies, car dealers, regular customers who own their own businesses.
Cash is still the best prize motivator.
Each week, the 3 semi-finalists get a prize. Three of the six finalists get cash or prizes. One sounds much more exciting than the other. Use global terms in all your marketing plans. The bigger, the better concept.