It might be easier to have cron delete the folder and recreate it every x hours.
create a folderclear.php file:
<?php
//delete the folder
rmdir(/path/foldername);
//create the folder
mkdir(/path/foldername);
?>
Then have cron run the folder to lynx on your interval:
lynx -dump -auth=username:password http://yourdomain.com/password_protected_folder/folderclear.php
I would keep the php file in a password protected file so only you can delete the folder