Flat field illumination of an 8mm frame should be very easy- make sure your optics are >> bigger than 8mm is all. You might like to look at a recent thread on sci.eng.lighting (???), where the question "how is colour correction in scanners done with discharge light sources or fluorescents ?" was asked about a month ago. A Google groups search should yield the info you need.

Why not buy a good pro digital stills camera, with a firewire interface and start from that. You might get one with uncompressed frame output. Last time I looked Morgan had some lovely Minolta pro cams with a suitable spec. Screw the warranty... The resolution should be close to the theoretical on a 4 meg imager, even allowing for the loss for colour.

Steve