WordPress.org

1. Upload mk-to-lat.php to the /wp-content/plugins/ directory
2. Activate the plugin through the 'Plugins' menu in WordPress
3. Go to Options->Permalinks and change from Standard to Custom and in the field below add:

/%category%/%postname%/

Thats it. If you have any previous posts with cyrillic titles, you may have to edit and save them again for the url friendly urls to appear.