1.Set up a mission with the player and subordinate near a small obstacle, such as a bag fence.
2. Have an enemy unit start out hidden from your squad, but give it a waypoint to move out in front of the bag fence.
3.Launch the mission.
4.Order the subordinate to move to the ground directly behind the bag fence and tell it to go into combat mode. It will lie prone at that point. However, if you order the unit to move to the "House Position Slot" attached to the bag fence, it will stay crouched instead.
5.Once the enemy unit is visible, order the subordinate to target the enemy and engage. He will most likely get up and move before shooting.
Here is a short video demonstrating the effect: http://youtu.be/SZnGalqOpac