From Jomres v4 manual

General description

Jomres supports SEF urls by using sh404sef or default Joomla SEF. This support is limited to Joomla 1.5 only.

sh404 SEF support

The options in this tab will only show up if you have sh404sef installed. When you first install you will need to manually move a file from the Jomres main folder (/jomres) to the sh404sef's external extensions folder. The full paths are given in this tab. Once you've done this revisiting this tab will provide you with several configuration options you can use to implement SEF urls in Jomres.

Note that while our support is officially limited to sh404sef and Jomres integration it is understood that the sef plugin in Jomres may also work with artio sef too, but this is outside of the scope of our support so you're advised to experiment yourself to get this working.

Default Joomla SEF support

Jomres offers support for default built-in Joomla SEF. All you have to do is copy router.php located in /jomres to /components/com_jomres/ and the sef will work automatically.