I'm almost 100% sure that Scott Stapp doesn't do any of the amazing solo work that you hear on live recordings. Tremonti is so GREAT why would you want to waste his talent?
BUT when I went to a Creed concert last summer Stapp did play guitar to keep the rythmn down during "Stand Here With Me" while Tremonti did the solo you hear on the album. Plus, in the 1st issue of CreedINK magazine Scott mentions that he's working on his guitar abilities and it will be incorporated more in upcoming albums and tours!!!