Step 1: What You'll Need
1 x Reflector Mount (a friendly bike shop will give these away for free)
1 x Shim for reflector mount (also probably free at your LBS)
1 x 2 inch 1/4" x 20 thread count screw of your choice (pretty standard for most cameras)
2 x 1/4" wing nuts
2 x 1/4" washers
2 x 1/4" rubber washers
You might also need a drill with a 1/4" drill bit
Step 2: Drill Out Hole
You can use a mount that has only one hole, you'll just have the mounting screw double as the screw for the camera. Make sure you take into account that you'll need a 1/4" diameter hole through there when rummaging through their reflector bin.
Step 3: Assembly
wing nut (could also use a regular nut)
wing nut (upside down! this one is more helpful if it's a wing nut)
the rubber washers were to help absorb shock. it's not perfect, but it does a better job than nothing. still looking for an improvement on that though.