Well on the PSX all the battle models are contained in the ENEMY folders, the battle models for the main characters are in ENEMY6. However, when you swap a model of a main character and an enemy the game will crash which proves that there is a difference between models supposed to be fiends or friends. Thats also why he said "Reskin Dyne" not just swap the LZS files.
To reskin you need to go into Barrets battle model and map out his graphical data. For PSX lazy bastard has compiled a breakdown for us
http://forums.qhimm.com/index.php?topic=13501.0The bone data section at 28c is the important stuff. But the bone description is also important if it is different between Dyne and Barret. You have to take the parts of Barrets model and strip them over Dyne's Skeleton. That means alot of hex editing, testing, understanding, succeeding.