URL to run garbage collection only

This may be a feature request but maybe the functionality already exists.

Does WP Supercache have a URL that can be accessed to fire garbage collection and nothing else? I know that it adds the schedule to the wp-cron, and that it runs when wp-cron.php?doing_wp_cron is accessed, but some plugins e.g. BackWPUp can generate tasks which can be fired outside the regular cron jobs e.g. wp-cron.php?backup_run=ext&jobid=2

This would be handy as I would like to run garbage collection every 30 min but run the entire wp-cron perhaps only twice a day during times of low website activity (I have 1000s of scheduled posts so the full wp cron job is a resource intensive process)

Thanks!

http://wordpress.org/plugins/wp-super-cache/