If you are lifting by the frame or with hydraylic levelers, do not lift all four wheels off the ground at one time. You could flip the shackles and that is a pain in the %%%%% to fix.
I would not jack a wheel up like in the pictures unless I had a jack with a large enough head to fit over both U bolts or some other type of pad. There is too much weight on a very small area the way the picture shows. I suspect that is why the axle mfg recommends using the frame.