Steve - under certain circs you can send out skirmishers from battalions. It's easier when you've got 36 fig French Napoleonic battalions and you can simply say, one of those six companies was the light company so we will field 6 figs from each battalion in the brigade as a skirmish screen.
With the small AWI battalions you might wish to discuss this before setting up a game. So a simple example: you have an American brigade consisting of three 18 man battalions, which you decide to field as three 16 man battalions and a 6 fig skirmish unit. Or you might have a brigade with two 16 fig battalions and on 12 man one - you decide to break throw the small one forward in skirmish order.
EC