Entering the Passphrase through stdin

[Richard L Ross]

Running a mix of OpenSSH 4.3p2 and 3.8.1p1 (AIX5.3, Fedora 5  and Cygwin).  Is there a capability or way where the passphrase can be read from stdin vs tty?  Some other SSH implementations have a '-p' option to perform this.  Looking for a way to automate entering the passphrase during the ssh-add process.

Thanks
Richard Ross