Basic mechanics: how do you actually manipulate upper control arm alignment cams?

You can try reading these threads:

Front end rebuild 1972 Duster

Alignment at home and aftermarket UCAS too.

To answer your specific question though, I loosen the nut on the alignment cam to where it stays in place but the cams can still be rotated. I leave the wheels on. Usually I can reach the front cam with the car at rest but to reach the rear cam, I often have to lift the car to create some room to reach in.