My plugin Custom Post Permalinks allows you to set permalink structures for custom post types and it supports post authors as part of a permastruct. However, while my plugin will enable you to set up that structure, I don’t suggest using that structure. That structure will essentially make WordPress interpret all top-level pages as 404 errors (and second level pages, I think). You should be fine if you add the post type to anchor the beginning of the structure like this:
/%post_type%/%author%/%postname%/