But, xaxis, the matrix of the camera would get hot very quickly and you'd get a lot of noise on the pictures, unless you've got a FC block for C5Dmk2 :D
It would be more possible if you'd made exposures like 15minutes, and then stack them. And if Ian would position camera at the North Star it would take looong time, it would be better to shoot at the edge of the Earth, ( hope you understand me, I mean not at the North Star but at the edge of planet, ) because then the stars rotate faster, and it would not take 24hrs to make a full circle, but much less time. Like this:
http://www.flickr.com/photos/_belial/3627855977/