Thank you for your later notice about the RootsWeb site with Seminole Indian War rosters -- your research into this subject really progressed swiftly! You have a great treasure in your ancestor's account of his military experiences. Would love to read the account (translated) if you ever decide to post it.
My ancestor James Griffin from Wilcox County was a sergeant in those wars, and other relatives served as well -- Albrittons from Wilcox County, James Batchelor from New Orleans & Greenville, AL, and other men from Butler-Wilcox-Monroe-Conecuh-Lowndes-Montgomery / central Alabama counties area.
The Alabama Department of Archives and History in Montgomery (AL) has various material on the three Florida Indian Wars, alias Seminole Wars, and not all just on Alabama militia since men from all over the South were involved. You might contact one of the archivists there and ask about your ancestor and his unit.
For people searching for Alabama ancestors in this time period, see the Archives files: "Index to compiled service records for Alabama soldiers in the Florida Indian War, 1836-1838" copied by Robert C. Horn from National Archives microcopy M245. It might save a trip to the National Archives or a waiting period if you're considering ordering those records on LDS microfilm.
An old book resource but an interesting one is: "Reminiscences of the Second Seminole War" edited by John K. Mahon (Gainesville, University of Florida Press, 1966).