I've been very successful using the Hurricane Mini Pump Mount kit from performance.
http://www.performancebike.com/shop/...slisearch=true
I cut off each snap fitting and use them separately. The size is perfect to snap in a Dinotte light. I've used other mounts to attach to a seat stay and a seat tube. The snap holds the light securely and I've had no problems with them detaching. It makes a much more elegant mount than the "O" rings and allows for mounting where the "O" rings are not an option.