By various Texas Militia Acts, the state was divided up into a number of militia districts [brigades] comprised of two or more counties. A large number of the records relating to these units burned in the capitol fire, so records are fragmentary. The State Archives does have incomplete files on the various militia brigades, but most of them are very incomplete. There are fragmentary muster rolls together with a card index, but they are not complete. The actual muster rolls are extrmemely fragile, and are no longer accessible. The Archives was doing a very slow project of having the General Land Office doing high quality digital images of these rolls, but I don't know how far that they have gotten on them.

It will probably take a trip to Austin to answer your question, but be prepared to be disappointed.