Well a little surfing turned up an interesting site: http://www.10thpa.com/DrillCo1.htm. This shows marching drill, Firing Drill and Skirmishing Drill.
The skirmishing drill looks like it will be easy to apply to the table top. The firing drill is interesting. There is fire by company/platoon, fire by rank, oblique fire and fire by file. Company/platoon fire would match rather well to firing as a formation in the existing SP rules. Oblique fire would allow a formation to fire on an angle rather than directly ahead. The fire by rank seems also easy to replicate as only one rank would fire per initiative at a time. The firing by file though would seem to be much harder. I was thinking that only 1/4 of the formation would be allows to fire per initiative. This way a portion of the troops will be able to fire at every initiative for muzzle loading rifle armed troops (most troops).