The trick is using a foam roller, and the ink that I was recommended is Jacquard Textile/Fabric ink. The typical fabric screen printing ink smudged and slid all over the place. The fabric ink lays down very nicely and leaves a rough transfer of the image, which looks cool and very handmade.
Process: I rolled the ink onto by block print design, then flipped it over on top of my fabric. In this case, I was printing on organic cotton and bamboo blend dinner napkins. I applied pressure to the block using a few scrap pieces of wood. I pressed as hard as I could for about ten seconds to achieve a good transfer. Here's a few pics of my morning printing session. Enjoy, and good luck with yours!