<?php
/*
Plugin Name: Example Importer Plugin
Version: 0.1
Plugin URI: http://nazgul.nu/blog/
Description: Bundle an importer in a plugin.
Author: Nazgul
Author URI: http://nazgul.nu/
*/

require_once(ABSPATH . 'wp-admin/includes/import.php');

register_importer('importerplugin', __('Importer Plugin'), __('Import ...'), 'importerplugin_dispatch');
add_filter('importer_path', 'importerplugin_import_path');

function importerplugin_dispatch() {
	// Write your importer code here
}

function importerplugin_import_path($text) {
	if(stripos($text, ABSPATH . "wp-admin/import/importerplugin.php") !== false)
		$text = str_replace('wp-admin/import', 'wp-content/plugins', $text);
	
	return $text;
}

?>