Ambient Occlusion (at least, the popular ray traced kind) will not be possible as a Python script, unfortunately. This is something that would need to be implemented as a shader node, like in Pixels:3D. However, we have been using something incredibly similar to AO for a long time now: These "global light sets" are very close to depth map based AO, see this page. Looks familiar, doesn't it? You can actually bake AO to textures and use them in Poser. I did that with a custom shader in Pixels that would export me the rendered shading a as a texture, but it still needs some major improvements. It should be possible to do it with pther programs that support texture baking, e.g. 3ds or C4D.