create email can be:-send_email
for the -generate-password flag if it were me I'd grab 7 (or 11) characters from /dev/random and force the user to change a password on login.
Email subject and body should be the same as system-generated email when you send email for a new user created from the web interface (reuse the same bit of code). I'd be more than happy to compose or look at that if someone thinks that would be useful.