Sivana, Poser (versions 6 and 7) can render coloured textures in b/w if you use the material room. Insert a Math->hsv node between the root node and the image_map node and set saturation to 0. You would have to do that for all materials, but it can be done in Poser. Here's a picture to show what I mean (click it to see it bigger). The SkinHead material is the only one I've added the hsv node to to show the effect. As you can see, the neck, the lips and if you look closely the lacrimal is still in colour, but the face isn't.