Adjust the color using the color head and the daylight setting for white balance. This will give you an image that can be inverted without major curve adjustments, resulting in cleaner scans. However I have not had great luck scanning color negative films with a DSLR. Some colors just don't come out quite right. But I definitely got better results using a color head than using a plain white bulb.
My method to adjust the head was to include the border in a shot and then adjust the colors to bring the white peak of the histogram so all channels were aligned. It's pretty easy to do with a bit of experimenting. Then adjust the exposure so the peaks from the border are all the way to right an clipped a tiny bit. When you inver this will give you the cleanest highlights.