My question might also be put, "What does System Preferences -> Users & Accounts do to change a user's password that I'm missing in the command line?"
The desktop is joined to both OD and AD directories. I can change my own user's auth with
$ passwd <uname> ... (update pwd through dialog) ... $ dscl . -passwd /Users/<uname> ... (update through dialog) ...
However, I can't use it for other users. I just get a dscl error -14009 (eDSUnknownNodeName). It doesn't matter if I use a full admin account, sudo -s, or anything.
What else might I try? I really want to be able to do this through terminal so I can write a bash for loop to change the passwords more easily.