I think that website is trying to sell some kilts, not go for historic accuracy! Various units of the Confederate military wore widely different uniforms. I don't think any of them wore kilts, but I'm no expert in this area. I know many officers and men wore parts of their US Army uniforms in the beginning. If you look at the movie 'Gods and Generals' which is a pretty accurate depiction of the first months of the conflict, and 'Gettysburg' also pretty accurate, and you'll see everything from US Army to VMI cadet uniforms, as well as some unique state guard uniforms and homemade / civilian clothing adaptions being worn by Confederate troops.