I'd like to overwrite the way this file works:

    app\code\core\Mage\Catalog\Block\Product\View\Options\Type\Select.php


I thought all I had to do was copy it to:

    app\code\**local**\Mage\Catalog\Block\Product\View\Options\Type\Select.php

That does not appear to be working. Is there another option available?  My goal is just to change the HTML that is used here.