I am no expert for SCO, but in most UNIXes (and i presume in SCO too) the passwd utility clears the buffer before using stdin, which is the reason why a pipeline won't work (in fact this is the desired effect - passwd is not supposed to work that way).

You can use a program to emulate an interactive session like expect to do what you want. See the expect manual for details, but it quite straightforward: you look for a certain prompt and then feed it a string, the program will think the string was entered by keyboard.

I hope this helps.

bakunin