Okay, finally got the plugin installed on the non-git version with 3.1.2, but when putting the <wpg3> tags into a page, this is the error I get when viewing it:
Fatal error: __clone method called on non-object in /home/crickie/crickie.com/wp-content/plugins/wpg3/wpg3_class_WPG3_Xhttp.php on line 178