You can't convert an obp file, but you can take your boolean model and turn it into an obj file (there is now a "C" at the bottom of the object menu that I would assume stands for "Convert to Mesh").

Once you have converted the object to a mesh, you can export it, and then import it into Poser.

I looks like Bryce also creates UV maps for the saved obj, although I'm going to have to look into that a little further.  I was playing with creating some boolean models in Bryce and I suddenly found all sorts of UV maps had been created ... but, when and how, I have no idea.

Could be worse, could be raining.