I dont have any clue for how to do this either..but may be this is the way forward... may be someone else from the group can help u sorting out this messy script to tell how to do this :-)
#! /bin/ksh
DELAY=1
OLD="oldpasswd"
NEW="nepasswd"
passwd |&
sleep $DELAY
print -p $OLD
sleep $DELAY
print -p $NEW
sleep $DELAY
print -p $NEW