Experiment. Think about it logically. The spec map on that example is very noisy. Use a noisy photo overlay and give it a shot. Add color to your spec map to add variety. Try things out! :) You could use the leather diffuse as a base for your spec map, then modify/adjust it to get the result you want.
I've been having trouble creating a soft leather material. I've been able to find a lot of info on how to make spec maps for hardsurface stuff but not too much on this material. From what I understand it would be a dark, mostly plain diffuse and all the work would fall on the spec map. Does anyone have any tips on how to…