You should also be able to find a conduit clamp that might work. Check at the hardware store or home center. The clamps are designed to hang thinwall electrical counduit and are available in various sizes..
The frames aluminium too, that could cause problems (not sure though I'm not a welder).
That frame adaptor kit can be hand made pretty easily, I just used a drill and a hacksaw to make up the adaptor plate (a rectangle of thick sheet metal, with three 6mm holes drilled into it. note: the outer holes must be aligned with the holes on the engine for the front mount.) and brought some long M6 bolts that I then cut to size. Next you need to drill a 6.5mm hole through the frame for the long bolt to go through. Check out the image of it done on my bike (exact same model as yours). Theres a detailed install guide here http://www.zippycycles.com/instruction_manual.html about half way down the page it tells you how to do the frame mount. I would suggest putting some thick rubber in between the frame and the mounts, this stops the vibrations from damaging the frame and makes it more comfortable to ride.