Stabbing in the belt is not an issue. What I have in mind is stropping the edge of your knife like barbers do with their razors and as Ray Mears does in this video:

http://www.youtube.com/watch?v=0a2Jm3pkXqk

What kind of leather belt is ideal? He's doing it on the inside of his belt, is it on the rough side of the leather? (There is the grain layer, the corium and the rough)