Last time I played there was an interesting situation:
Dark riders were coming around a forest, they could just see a dwarven bolt thrower, the crew standing behind their machine.
The dwarf could move the machine 3", just moving out of LOS from the DR. However, the crew had to move more than 3" to be out of LOS.

Now what is the correct way:

a) The machine itself can only move 3" and then the crew can be placed within 1" of the machine. But by doing this, they can be moved more than 3".
The reasoning behind this is that they're constantly running around the machine, pushing and pulling it to reposition it.

b) The crew can never move more than it's allowance because warmachines (as a unit) can not march.

Let me know what you think