Direct one of the mercs to travel a longer distance than the available action points. Watch the action point total as it decreases. When the action points are below the number needed to shoot, but still more than zero, click the Right Mouse Button on the merc to spin it around and display three buttons. Click on the "Reserve Points" button, which should have been unchecked previously. Click the Right Mouse Button on the merc to spin it back. The merc will continue walking to the destination while ignoring the action point limit.