Units that can skirmish can either be in regular formation (like all other troops) or in skirmish formation.
A unit capable of skirmishing can spend a movement phase to change from regular formation to skirmish, or from skirmish to regular formation. A unit changing formation may still shoot the turn it does so.
Move the skirmishers into contact by the most direct route (turn each model to point at the enemy and charge in a straight line). If this gets models into contact on the enemies flank, we allow it. Note that the unit does not get a combat resolution bonus for attacking a unit in the flank.
The unit in skirmish formation suffers the same amount of damage as regular units.
House Rule: It is suggested that when chariots and Night Goblin Fanatics damage units in skirmish formation that the number of hits be reduced by 1/2, minimum 1 hit.