@realsurf - so were your photoshop experiments successful? If so, you could either use After Effects to achieve the same effect or you could batch process several single images. I suggest this since your example has an illustrated look that I feel could give you usable results quicker than tuning shaders. Why? 

momodot's render has some interesting light / shadow play that mimics your example photo. Foreground beer guy has at least eight different skin tones based on how much light or shadow the skin receives. Even his lips have four colors. Part of what makes that possible it the texture, but alot of it has to do with the forms underneath the skin, how it affects the skin above it and how that skin interact with light and shadow.

I lack the artistic term to describe it, but seems to me that illustrator look (markers maybe?) would be easier to achieve with Photoshop / AE once you've rendered a thorough light study.