Maybe a D6, with ones counting as twos or threes. The basic units are small, but not necessarily single elements. There is basically a 90mm frontage and a varying depth according to figure type for each unit, which tend to be battalions or regiments or batteries for the regular armies. For 6mm, they recommend a fixed base with the figures mounted deployed and a separate marker, possibly with an officer on it, that indicates the fornt of the unit, so if he's at a short end it's in column. 15mm troops go onto three bases of 30mm frontage and can be arranged in line or column to show the two orders.
Officers are a separate small element that can be attached to a formation.
Overlying the PIP rules for command control is a written orders system. Handling this something like Shako, with the officer moving down the arrow would probably work well, though PoW is less detailed and methodical on this point. Each posture has certain requirements, and your PIPs have to be spent to fulfill them. There is again some grey and fuzzy space in the exact implementation of this. Unlike DBM and more like most other miniatures rules, there are morale checks and attritional casualties.