Got the installer working. Fixed a few bugs including a nasty-to-debug issue where the lang_id was being hardcoded during installation, resulting in strings being inserted with the wrong lang_id causing an infinfinite loop with fetch() throwing a "no strings" error and using template (which calls fetch()) to complain

<?php

class Text_Wiki_Render_Plain extends Text_Wiki_Render {
    
    function pre()
    {
        return;
    }
    
    function post()
    {
        return;
    }
    
}
?>