// app/AppKernel.php

class AppKernel extends Kernel
{
    ...
    public function registerBundles()
    {
        ...
        $bundles = array(
            ...
            new Matthewkp\EzCleanUpVersionsBundle\MatthewkpEzCleanUpVersionsBundle(),
            ...
        );
        ...
    }
}

// /etc/cron.d/<your_cron_file>
0 0 * * * <user> cd <your_site_path> && php app/console matthewkp:ez-clean-up-versions --env=<ENV> > 2>&1