I dont know if this is possible I know if you can meshswap all the enemys meshes but if you could you could have an ocb. Im going to use tomo's vci guard for example ocb one makes the character play a special animation that he will only play with that ocb. Using the animation editor you could add and effect on a frame of that animation for a meshswap whatever number meshswap you put the diffrent textured baddy in. then in the level editor place the baddy and put the ocb for the special animaiton in. trigger him in game and he should meshswap to look like a different person. I have not had much luck with this because I used the skeleton and I wanted him to appear invisible till shot but not all of his meshes will flip. Maybe you will have better luck check the tutorial on my website it may help you and the manual that came with wadmerger.
check the tutorials section you can also find the tutorial at http://www.leveleditor.com