I went to a windsurfing shop and asked for an old boom (got one free of charge!), then sawed the actual boom of so what was left was the clamp and 10cm of tubing.
The clamp fits around the spi-pole perfectly, if you dont have a spi-pole you could probably fit it to the boom as well.
Here's a video that I took last year (Youtube ), even though the conditions where quite rough the image is clear and stable.
The only problem was the narrow camera angle but this something I should work out sometime.

Clamp:

BTW, the camera was a GoPro Digital Hero 3