It is possible by using a stencil map. Instead of using two textures, as in the documentation example, you just use the stencil map & texture map (in this order, top-bottom). Where the stencil is white it will show the texture, where is black it will show the color (or viceversa, I forgot )
Linux Mint DE 64bit | Blender 2.62 | Yafaray 0.1.2 beta, matejmo.deviantart