Some people use glue (fabric or hot) to add traction, either by applying a thin layering/coating to the bottom or little balls/circles (dots). I have also seen some people paint squiggly lines.
As for actual leather type patch soles KnitPicks and Patternworks sells some, I believe instructions are included.
I've also seen non-skid patches used in the home (bathroom, kitchen, etc.) recommended on some blogs but I wouldn't advise that method.