Easy peasy. Just add the following code to your site's .htaccess file:
php_flag apc.cache_by_default Off
Why would you want to disable apc caching? I've personally had issues with Wordpress sites when updating them. It's usually a good idea to temporarily turn off the caching, update Wordpress, test to make sure the site works,then turn the caching back on.
Why? Keeps you from having to restart apache.