In DS 4.5 there is a quick and easy way to create clothing textures, and it’s actually very, very good.
Load a tileable pattern as a texture map onto an article of clothing.
Scroll down in your materials, and set the horizontal and verticle tiles to 5 or 10 each, whichever looks best.
Then go to the shader baker and bake them…. you’ll probably want to up the resolution to 1500+
This will create a nice cloth texture that you can play with.
I found this site which has a lot of tileable cloth:
http://speckyboy.com/2010/07/28/50-tileable-and-seamless-pattern-sets-500-patterns/