Inspired by the upcoming Lomography 35mm scanner and based on the previous test I did for digitizing 120 film, I put together a simple wooden stand to hold my camera over a 120 film negative that has been placed on a light table. I made masks for the negatives to hold the film flat and to shield the camera from flare from the light table. I made the stand to shoot my 6-12 negatives from my Belair, but a shorter stand for 6x6 and 6x9 negatives will maximize the scan for the smaller negatives. It would be more elegant to make an adjustable stand, but for now, the fixed height stands are very easy to make.
After shooting several negatives, I found I needed to cover up the sides and the lens opening in order to prevent reflections from the overhead light from showing on the scan. I just used the same black card stock I used to make the negative masks.
I plan on making another stand specifically for 6x6 negatives in order to maximize the scan size and resolution.