// get the "author" role object
$role = get_role( 'author' );
// add "organize_gallery" to this role object
$role->add_cap( 'unfiltered_html' );
Basically, you are just giving the author user role access to post any kind of code they want by adding the 'unfiltered_html' capability. Just make sure that you can trust all of your authors before adding this, because without html filtering, a user could do considerable harm to your site if they decided to post some nasty javascript.
