David E. Johnston of the 7th Virginia provides some information on locations and movements in his book, http://docsouth.unc.edu/fpn/johnstond/johnston.html

I have not studied the campaign that much, but have identified the Rockbridge Artillery position north of Fort Gilmer. Separately, I have also found a detailed account mentioning guns under Chamberlayne, the Washington Artillery under Major Miller, Rice's battery and a Whitworth gun in an account by David Gregg McIntosh, in the Petersburg line between batteries 31 to 45, to include Fort Lee and Fort Gregg (McIntosh Papers, microfilm, Virginia Historical Society, Richmond).