Hi, just returned from a weeks break. I used an old slide projector 70mm focal length, but any old standard lens will do (50mm). The idea is to reverse the lens so that the front side is connected to the front of the digital lens.
I used duct tape to connect them, not recommended though, if the lens retracts, it may cause damage. I've ordered a hood/ adapter which I'll attach the lens onto.
I don't remember the subject to lens distance but it of the order of 10mm. Idea is to use chdk to user a fast shutter speed to minimise camera shake if you are handholding, and to minimise aperture f8 for max depth of field, which is narrow for macro work