Export WordPress Posts by category or custom taxonomy with attachments

gistfile1.php

<?php
/**
 * Export WordPress Posts by category or custom taxonomy with attachments
 * 
 * Add the needed select boxes to the ui
 */
add_action( 'export_filters', 'export_custom_taxonomy_fields' );
function export_custom_taxonomy_fields() {
        ?>
	<!-- Styles -->
	<style>
	#custom_taxonomy_post_filter ul {
		display: inline-block;
		padding:20px;border:1px solid #eee;margin: 5px 0;
		background: #fafafa;
		-webkit-border-radius: 3px;
		-moz-border-radius: 3px;
		-o-border-radius: 3px;
		-ms-border-radius: 3px;
		border-radius: 3px;
	}
	#custom_taxonomy_post_filter ul label {
		width: 120px;display: inline-block;
	}
	#custom_taxonomy_post_filter ul select {
		min-width: 150px;
	}
	#cat {
		display: none;
	}
	</style>
	
	<!-- Taxonomy box -->
	<li id="custom_taxonomy_post_filter">
		<ul>
			<li><h3><strong>Filter by taxonomies:</strong></h3></li>
			<?php
			
			// Get all post taxonomies
			$taxonomies = get_object_taxonomies( 'post' );
			
			// For each taxonomy get a select input with al terms
			foreach ( $taxonomies as $taxonomy ) {
				$tax = get_taxonomy( $taxonomy );
				$name = $tax->labels->name;
				$terms = get_terms( $taxonomy );
				?>
				<li class="custom_taxonomy_post_filter">
					<label for=""><?php echo $name; ?></label>
					<select name="<?php echo $taxonomy; ?>_custom_taxonomy_post_filter">
						<option value="0"><?php _e( 'All' ); ?></option>
						<?php foreach ( $terms as $term ): ?>
						<option value="<?php echo $term->term_id; ?>"><?php echo $term->name; ?></option>
						<?php endforeach; ?>
					</select>
				</li>
				<?php
			}
			?>
			<li class="checkbox">
				<label for="export_attachments_ctpt">Export attachments</label>
				<input type="checkbox" id="export_attachments_ctpt" name="export_attachments_ctpt" value="1" checked/>
			</li>
		</ul>
	</li>

	<!-- Add our new Taxonomy box -->
	<script type="text/javascript">
	//<![CDATA[
		jQuery(document).ready(function($){
	 		$('#post-filters').append($('#custom_taxonomy_post_filter'));
		});
	//]]>
	</script>
	
	<?php
}

/**
 * Add a filter trough the only action present in includes/export.php
 */
add_action( 'export_wp', 'edit_default_export_query' );
function edit_default_export_query() { 
	add_filter( 'query', 'edit_default_export_query_filter' ); 
	add_filter( 'query', 'edit_default_author_export_query_filter' );
}

/**
 * Edit default export query behavior
 * 
 * @var String $query Wpdb query
 * 
 * @return String Wpdb query
 */
function edit_default_export_query_filter( $query ) {
	
	// Applied only to first query
	remove_filter( 'query', 'edit_default_export_query_filter') ;
	
	global $wpdb, $exported_posts_ids;
	
	// Only for posts export
	if ( 'posts' == $_GET['content'] ){
		
		// Get all post taxonomies
		$taxonomies = get_object_taxonomies( 'post' );
		
		// Build where clause
		$where = '';
		foreach ( $taxonomies as $taxonomy ) {
			$taxonomy_field = $taxonomy . '_custom_taxonomy_post_filter';
			if ( (int) $_GET[ $taxonomy_field ] )
				$where .= $wpdb->prepare( " AND {$wpdb->term_relationships}.term_taxonomy_id = %d ", (int) $_GET[ $taxonomy_field ] );
		}
		
		// For testing purpose only
		// $where = $wpdb->prepare ( " AND {$wpdb->posts}.ID = %d ", 6332 );
		
		// Build join clause
		if ( !empty( $where ) && false === strpos( $query, 'INNER JOIN' ) ){
			$join = "INNER JOIN {$wpdb->term_relationships} ON ({$wpdb->posts}.ID = {$wpdb->term_relationships}.object_id)";
			$join_position = strpos( $query, $wpdb->posts ) + strlen( $wpdb->posts ) + 1;
			$query = substr_replace( $query, $join, $join_position, 0 );
		}
		
		// Rebuild query
		$query = $query . $where;
		
		// Export attachments
		if ( isset( $_GET['export_attachments_ctpt'] ) ){
			
			// Get selected post IDs
			$exported_posts_ids = $wpdb->get_col( $query );
			
			// Build an array of attachement IDs
			$attachment_ids = array();
			foreach ( $exported_posts_ids as $post_id ) {
				
				$attachments = get_children( array(
					'post_parent' 	=> 	$post_id,
					'post_type' 	=> 	'attachment'
				) );
				
				foreach ( $attachments as $key => $attachment )
					$attachment_ids[] = $attachment->ID;
				
			}
			
			// Build the new query
			if ( !empty( $attachment_ids ) ){
				$attachment_ids = implode( ', ', $attachment_ids );
				$attachment_query = "(SELECT ID FROM {$wpdb->posts} WHERE {$wpdb->posts}.ID IN ( {$attachment_ids} ))";
				$query = "({$query}) UNION ({$attachment_query})";
			}
		}
		
	}
	
	return $query;
	
}

/**
 * Limit author export only to selected posts
 * 
 * @var String $query Wpdb query
 * 
 * @return String Wpdb query
 */
function edit_default_author_export_query_filter( $query ) {
	
	global $wpdb, $exported_posts_ids;
	
	// Check if its the author query
	if ( false !== strpos( $query, 'SELECT DISTINCT post_author' ) && !empty( $exported_posts_ids ) ) {
		// Applied only to first query
		remove_filter( 'query', 'edit_default_author_export_query_filter') ;
		$exported_posts_ids = implode( ', ', $exported_posts_ids );
		$query .= " AND {$wpdb->posts}.ID IN ( {$exported_posts_ids} )";
	}
	
	return $query;
	
}

How would you go about allowing this to work with a custom post type and its custom taxonomy?