Comment 46 for bug 283811

Rereading manheim comment ( https://bugs.launchpad.net/ubuntu/+source/cups/+bug/283811/comments/5 ),
about "DeviceURI smb://SomeUser:TopSecretPassword@/server/Canon-i950"
I now somehow recall to have read in 'man backend':
Starting with CUPS 1.1.22, any authentication information in
       argv[0] is removed, so backend developers are urged to use the
       DEVICE_URI environment variable whenever authentication information is
       required.
See this Mike's bug in 2004: http://markmail.org/message/2jbwl6jbcekjufqh

Still searching documentation for DEVICE_URI... not finding.
I am unsure how you are supposed to correctly export this info for CUPS to use it.