I'm not an expert on these matters but I don't think the dxf file from Poser contains sufficient information to provide proper colour mapping info to Bryce. I can't remember if Bryce 2 accepted other imports such as 3DS. If so, you might try converting your Poser obj with another program to 3ds (or whatever) for import to Bryce. Barring that, I'm afraid the only solution is to upgrade your Bryce.