How to set password of cups 1.3.7 (/etc/cups/passwd.md5) without prompting?

My company is using CUPS v1.3.7, I would like to allow users to be authenticated only in the cups web interface and not via SSH.

I imagine, i should use the authentication type BasicDigest in cupsd.conf.

AuthType Digest

Then i have to use lppasswd -g mygroup -a username to add the access to cups to the user.

lppasswd -g mygroup -a username
Enter password :
Enter password again :

But, if i allow my user to type some password, i would allow them to access ssh, what i do not want to.

How can I set the password of a user without prompting (possibly scripting it)?