I've now made the specular texture for Fat Face. It's been mostly a question of taking the various diffuse layers and adjusting their brightness and levels or turning them off in the case of things like the tattoo and camo patterning.
There's been a bit of custom painting like the shiny nose but not much.
While I was at it I touched up a couple of dodgy bits on the normal map. Following Ben Mathis' tutorial method of doing it one channel at a time made it much easier. Re-normalising after of course to prevent weird lighting.