i can't give you a technical answer to this, but i can say that i have seen several cnc mills (haas) installed and moved and a couple of cnc lathes (damn if i can remember what they were, i don't run those.) and i have only seen it done with fork trucks, even when an overhead crane was available. take it for what it's worth.
i can say also that the balance points on cnc machines always seems to be somewhere other than the obvious. probably cause you can't actually see the heavy bits under all the cowling and stuff.