Modificando Wordpress para criar post type e suas taxonomy...

register_post_type

/*===================================
=            Posts Types            =
===================================*/

/*==========  Exemplo  ==========*/

	function exemplo() {
		$args = array(
			'labels' => array('name' => 'exemplo', 'add_new' => 'Adicionar'),
			'public' => true,
			'publicly_queryable' => true,
			'show_ui' => true,
			'show_in_menu' => true,
			'query_var' => true,
			'exclude_from_search' => true,
			'rewrite' => array( 'slug' => 'exemplo' ),
			'capability_type' => 'post',
			'has_archive' => true,
			'hierarchical' => true,
			'taxonomies' => array('categoria-exemplo'),
			'menu_position' => 2,
			'supports' => array( 'title', 'editor', 'tags', 'author', 'revisions', 'excerpt', 'comments', 'page-attributes' )
		);
	
		register_post_type( 'exemplo', $args );
		flush_rewrite_rules();
	}

	add_action( 'init', 'exemplo' );

register_taxonomy

$args = array(
	'hierarchical'          => true,
			//'labels'                => $labels,
	'show_ui'               => true,
	'show_admin_column'     => true,
	'update_count_callback' => '_update_post_term_count',
	'query_var'             => true,
	'rewrite'               => array( 'slug' => 'categoria-exemplo' ),
	'exclude_from_search' => false,
	'publicly_queryable' => true,
	'public' => true,
	);
		
	register_taxonomy( 'categoria-exemplo', 'exemplo', $args );