Default [Q] backing up specific directories automatically

Hi, how do I backup selected subdirectories such as the ones with project files or the one with my books. These are not subdirectories under specific apps. They are stand alone such as: /storage/extSdCard /documents and /storage /extSdCard /books. I've written the developer of helium and tested backup pro but the apps don't do this. I know it's possible to back up specific files but I have too many for this to be practical. How do I set up scheduled backups of directories with their subdirectories?