Changing the Blending Value to 1 then gets the second texture showing, as seen at the bottom of the PoserSurface node. You would obviously have to do the above for all bodyparts, and again for bump maps if you used them as well. For my little anim I set frames to 16. I set a keyframe at frame 1 using the material room settings from the first pic. I then went to frame 12 and set the zombie morph value to 1, went to the material room and changed the Blending value to 1 and set another keyframe. Turning off Skip Frames in the anim menu and using full tracking and previewing the anim I could roughly see the desired effect. Hope that helps :)