I put the Slot X is leader, in the Control Keymaps.
And have the Spread Out - Mapped Key (which moves Groups as the target) in General Keymaps.

That way, it should apply to every toon on any team.

For your spread out mapped key, you will need to set the option (in the drop down box immediately below the Hotkey field), "Hold any Keystroke Actions while Hotkey is held" to "On".

The hotkey you use to initiate the movement should not matter, as long as it does not conflict with an existing IS Boxer or Warcraft mapped key.