You have two choices: you can either use a prop like the ones available at Ghastley's site (http://209.92.41.204/Poser) or you can paint it on the texture map directly and then morph the jawline to give the illusion of the raised surface. I recommend the latter, only because it looks more realistic. If it's for Mike, the Fantasy Beard from Daz is wonderful, but a real resource hog.