You could use P-clamps. I had to for my front fender because my suspension fork had no eyelets. Just take a photo with you to the hardware store--they aren't called P-clamps at all stores (once I described them in detail, the second clerk at the hardware store in the town I live near took me right to them). Here's a link that describes how you'd use them as well as photos. Good luck.

http://www.bikecommuters.com/2008/07...-your-friends/