Most search results point to Gen Edward C Walthall. Best found for Maj William T Walthall's Battalion are:

http://www.americancivilwarforum.com/the-boy-battalion-and-the-battle-of-chehaw-station-467.html
http://www.usgennet.org/usa/al/state2/talladega/wbts/campinstruction.htm

ADAH references Wallthall's Battalion as "light duty" men at Camp of Instruction, Talladega AL.

Best published description of Major Walthall's activities during Rousseau's Raid are found in David Evans, Sherman's Horsemen, pp 110, 111, 120-122.