Reynaldo Alvarez's ShortURL hack DOES work, but there are a few of glitches using it with Xoops. The problem is related to how the hack treats relative links and how the developers had coded their Xoops modules.

To make the hack fully operationable, you must be willing to make some changes to various module files. This little guide is intended to serve as "pointers", so you can follow and make the required change easily.

Requirement

In addition to the basic ReWrite requirement, your host company MUST have set session.trans_sid off in PHP.

PHP with session.use_trans_sid set will always add a unique PHPSESSID query pair to URLs if cookies are rejected (search engines do not accept cookies). While session.use_trans_sid helps users who do not accept cookies, but search engines will likely rank your sites low.

Why? Your sites may be considered as mirroring itself when search engines crawled your sites with the same URL appended with different session IDs. They may see that you are attempting to assign several URLs to the exactly same pages/contents, as a result, search engines may lower your rank or even ban your site altogether. And this will totally defeat the purpose of using the hack at the first place. So please make sure you don't have the session.trans_sid option set in your php.

A simple phpinfo() will provide you the information. You can disable that feature via a .htaccess file or directly from PHP code.

In the .htaccess file, you can add the following line:
php_flag session.use_trans_sid off

And in PHP code:
file: include/common.php
locate
session_start();
add
ini_set("url_rewriter.tags","");
before session_start();

If your PHP is compiled as Apache module, .htaccess will not work as the PHP master value will overwrite your local value. Only the second method will work, as it is a runtime modifier.

Make sure it works even you have made the necessary changes. Remove the hack if your URLs are still being appended with PHPSESSIDs.