I never got the Poser 8 Library to work and have resorted to some of the workarounds suggested in the threads that PhilC notated.  I currently use Shaderwork's Library python script, along with P3DO Explorer (when I need to find something quickly).

I mostly use Poser 7 for character design (because it's easy to save the progress) and sometimes when I'm putting together a complicated scene.  I'll then save the PZ3 file as a WIP and bring it in to Poser 8 to Render.