PIX ASA and Automated backups

Doe’s anyone have a good method of automating a pix backup , cisco ios kron can be used or archive but there doesn’t seem to be anything for pix , i can scp running-configs off but again i have to enter a password , i tried to script it from a linux box but the script stalls at the password input even tho i scripted the response , someone must be doing it , is there a command i have just missed ?