Unfortunately, Alan, that's the rub. If you are looking for officers in Louisiana regiments, I don't recall a source that lists ordnance officers. Thankfully, Art Bergeron made it lots easier in his book on Louisiana Confederate units when he listed the known field and company officers.
Yes, I know that it is more time consuming to look up each officer, but without another source to identify who held the position of ordnance officer, you have no choice but to consult Art's excellant work and look through those names or scroll through microfilm if those don't work.
I am just glad this board has so many interested and informed minds on here to help people whenever they can.