If someone tries to claim a bike without a slip, they'll need to show a photo identification to match the name on the claim check. Clearly post the hours your bike lockup will be open, along with a sign limiting your liability for loss or damage. Try contacting the Cascade or Northwest Bike Club or the Mountaineers. As with priority carpool parking, lots of good signage is important to direct bicyclists to the secure lockup location. See the Carpooling section above for more information about signage.
Incentives are usually in the form of reduced pricing or small prizes.
Here's an area where you can really use your creativity. If your event has an admission fee, offer discounts to those who show they arrived by bus, carpool or bicycle. Offering free or discounted food and drink is an excellent incentive to reward good transportation behavior. Offering discount coupons is good marketing for the concessionaire and a good incentive for you to provide. Remind concessionaires that it's likely that not all of the coupons handed out are likely to be redeemed, and that they enhance their reputation as an environmentally aware company by participating.