I have no idea how this plugin works. I had the impression that it just uploads albums and/or images to albums? What are these temporary images for?
Anyway, you need a place where they are not accidentally discovered as albums/images. So the choices of already existing Zenphoto folders are probably:
- the root of the /albums folder (since only folder within are considered albums)
- cache folder (you could even create your own cache subfolder folder maybye)
- uploaded folder