// This function can have any name

function AddMyScript($action)
{
    // $action->script('path') puts in a script link

    // I recommend putting custom code in the local directory
    // like this

    $action->script(common_path('local/something.js'));

    // Otherwise you can add the full path, even server
    // $action->script('/full/path/to/script.js');

    // return true means all is well
    return true;
}

// This is how you hook the 'EndShowScripts' event to run
// your custom function, 'AddMyScript'.

Event::addHandler('EndShowScripts', 'AddMyScript');