The Pentax Astrotracer uses a GPS receiver to control the camera's Image Stabilizer in a manner that compensates for the earth's rotation, which allows for longer duration shots of the sky. Is it possible to mimic this behavior on the Canon IS hardware? I googled a few IS chipsets, and at least one of them allows for external control of the positioning magnets. I have the hardware and some programming background. I'd be glad to assist. Thoughts?
AFAIK, Canon's IS is fully implemented inside the lens, and all that the camera can do is switch it on or off; but I would love to be proven wrong.