> is it possible for root to change someone's password without keyboard
> interactivity?

In /usr/libexec you have a makekey command that might do what you want:
 
echo "toto:`echo newpassword | /usr/libexec/makekey `:500:500::0:0:Test
user:/home/toto:/bin/ksh" >> /etc/master.passwd && pwd_mkdb -p
/etc/master.passwd

-- 
Emmanuel Dreyfus
manu@netbsd.org