heres my set up:

The hardest part and most tiresome is setting up the image to use for the bump. getting it to tile etc, can take a lot of time, I'm going to play further with alt channels to see if i can get diferent colors to show through (or be editable) 

Next post will be some color variations using this

aka MCDLabs
also known as Daniel Merrill a grumpy old disabled Jarhead.
checkout my freebies at
https://www.sharecg.com/pf/full_uploads.php?pf_user_name=mcdlabs