Although the MSG were initially mostly armed and equipped with what they could bring from home, there were large quantities of clothing and equipment purchased by James Harding (the MSG Quartermaster) from August 1861 onwards. For example I found an invoicce for the following purchased and shipped to Gen. M Jeff Thompson on August 28, 1861:-

600 pairs Satteen Pants
500 pairs Jeans Pants
400 Satteen Coats
100 dozen Hickory Shirts
50 dozen Undershirts
50 dozen Drawers
31 Wool Frocks
400 pairs of Shoes

This suggests a level of uniformity, even if not what would be considered a uniform.

There are many other similar invoices through late 61 and early 62 which would suggest that the level of clothing and equipment reaching the MSG was similar to that reaching units of the Confederate forces.