I have several of the Dosch texture packs. They are mostly in .JPG format (some I have are .PSD). The jpegs are certainly compatible with and usable in Poser - in that respect they are like any other textures. If Bryce can use jpegs then they are usable there, too. I don't have any of the models but if they are in a Poser-compatible format (e.g. .OBJ) then you can load and render them in Poser, but not pose them (unless you rig them yourself, of course).

Steve