./configure --with-sdin=yes & passwd --stdin

I need to set a passwd using a script.

Now, my distro doesn't seem to have the --stdin switch available.

What is the ./configure option to turn this on? I can't see it from 
./configure --help

(I need to do this because I need to set a new passwd without typing it in; 
ready for if I need to connect from an insecure, hardware keylogged, 
ssh-auth sniffed machine.)

If this is possible I'd like to request clear documentation about this added 
to the wishlist.

Thanks :)