I am adding a custom publish_type to Wordpress, and would really like the permalink structure to appear such as this:

/%post_type%/%year%/%monthnum%/%postname%/

I can not learn how to add the date tags. By using this code, provides me with /my_type/example-post-slug/:

register_post_type( 'customtype', array(
    ...other options...
    'rewrite' => array('slug' => 'my_type'),
));

How do you range from the dates?