No wonder I didn't find him, his record is found in the Confederate Miscellaneous File, not the Louisiana File, which is:

M347: Unfiled Papers and Slips Belonging in Confederate Compiled Service Records

Here is the only document I could find on the web regarding the St. Tammany Regiment

Saint Tammany Parish militia slave patrol order, 1862 Mar. 29.
http://beta.worldcat.org/archivegrid/data/264761157