Don't know about squares etc, but I have tried this for a few AWI battles and it has worked very well. Often I have been splitting my usual battalions of 18-30 figures into 6 figure companies to make a better game. This means that a small battle still gives 12+ units per side in 3 or 4 commands. As the figure/man ratio is the same then there is no need to fiddle with distances other than perhaps reducing the command radius of the "colonels" who replace the brigade commanders.
At this scale, and in the AWI, I ignore columns etc. companies are either in line or skirmish, but this could easily be tinkered with.
Units normally consist of 6 bases. If you base your units four figures to a base on 40x40mm bases, you'll get the most out of your Victrix figures. You may have to get a couple of additional unit command figures in metal, but that's no big deal. I don't know about the French, but with the British Flank companies and Centre companies boxes, I bought Centre companies and Highlanders Flank Companies. Then I mixed the arms between the two so that I had units with 6 Light infantry and 30 Centre. The Flank company figures all have the bigger shoulder pads or wings and are distinctive. My units are 36 figures.