As Moonboots says, it's not possible to do it in one fell swoop.
See other answer: it is possible. Below solution is still valid, if a little more fiddly, however.
I'd suggest moving each one individually. To ensure symmetry, type in how much you're moving the first piece by, then make sure you move the opposite piece the same amount in the opposite direction.
To make this answer more full: You do this by pressing G to move the object, then X/Y/Z to constrain to a given axis, then type a number. Your piece will move by this distance (default in most recent Blender versions: metric metres) in the positive direction of that axis.
If you press the - (minus) key, it'll swap and move the object in the negative direction of that axis.