It does work if you render your picture first, and then do the sketch render on the picture. That is what I did, the picture above is a sketch render straight from Poser6. It's like using Poser to add a filter effect, instead going to PhotoShop and doing it there.

Don Albert has some sketch presets for sale at DAZ that may give the kind of effect you are after, judging by your pictures.

http://www.daz3d.com/shop.php?op=itemdetails&item=2424