I needed a way to mount my NiteRider Pro series Headlamp to my helmet (Bell Super R2 ) which already has a Go-Pro Mount on top. The Go-Pro mount included with my helmet was better than the straps that the NiteRider came with so I decided to fabricate something that would allow me to use the GoPro Mount already on the helmet.
The updated version (here) has holes already in the model. Simply use screws that are already in the Niterider Helmet Mount to attach.
Use this in combination with the parts already supplied in your headlamp kit in order to construct the complete bracket.
You will need to provide your own screw (About 25mm long) in order to attach your mount to the helmet. This can be any generic screw and nut.