First, you'll need to copy Don, Judy, or whoever into your Poser 4 runtime. That means the CR2, the OBJ file in the geometry folder, and possibly the textures as well. Then, after you've spawned a morph in P5's Face Room, you can save the modified character to the Library. It'll help if you have P5's Library configured for multiple runtimes, because then you can simply switch over to the P4 runtime folders and directly save the character there for access in P4. If you're trying to create morphs for other figures than the P5 crew, you're on your own. I don't think the Face Room can be used in such a manner for Victoria, Posette, etc.; the geometry's all wrong. The Morph Putty tool might prove effective, though.