The enlarger is easy, the shutter is really not needed.
I tried to use flash method but really could not determine the exposure. As I don't have shutter on my enlarger, I used the 0.6 second exposure. Phil Davis suggest in his BTZS book time 0.4s (If I recall right) but I have to use longer to ensure get enough exposure. My enlarger's bulb need 0.1 sec for turning on and 0.1 sec for turning off (measured simply by recording movie with digicam. Precise enough).
My fear was that turning on and off times would not stay consistent and affects the exposures, but I didn't found any proof for that. The result is very consistent.
Before using enlarger, I tried to photograph step wedge by using various lighting systems. The light was always uneven. I also tried to tape wedge to window with and without diffuser but the background was always problematic (as did the exposure time during autumn/winter/spring).
One different approach is to photograph gray card and vary the aperture and shutter speed. I have used that a lot with MF and 35mm films as I have precise shutters in those cameras. With mechanical shutter I would not use that kind of test.
However it's easy way to get CI values. Or a rough charasteristic curve.
ps. I like to get flare in the results by photographing target, but as it's not an option with my equipments in large format cameras, I use contact method.
Also the flare depends on the lens and with large format cameras I have lot of very different lenses so inclusion of flare by photographing step wedges would require almost own test serie for each lens.
MF and 35mm lenses are good enough to have 'consistent' flare..