Permalinks and custom post types

Ideal, but no way to achieve yet (example):

post type archive : /projects
category archive  : /projects/project-category
tag archive       : /projects/project-tag
single post       : /projects/project-item or
                    /projects/project-category/project-item or
                    /projects/project-tag/project-item or
                    /projects/project-category/project-tag/project-item

Currently we use "Custom Post Type Permalinks" and not "Simple Post Type Permalinks" because it provides greater flexibility in the custom post types permalink structure.