Offer to appear as a spokesperson. You can organize your own media events. Television likes events with a highly visual component. When a car dealership raffled chances to win a car, they had the finalists wrestle in a pool of Jello to find the key. Every TV station in town sent a camera.
Newspapers tend to go for ideas, studies, and stories.
Make sure your spokesperson has plenty for the reporter. Make an effort to keep your association with a non-profit from sounding too commercial. Your involvement must be sincere. The audience is probably aware you are participating with the hope of getting publicity, but they will turn on you if it looks like that is all your company cares about. The cause you help benefits, your customers enjoy your participation, and you get the positive boost of good community image and the rewarding customer response it brings.