PGP 5.0 Secret Key Formats

Anyone know the format of the secret key (Diffie-Helman & DSS) in PGP 5.0 ?
and how to decode it if you know the passphrase ?

Thanks - Linz
--
Lindsay Mathieson
Black Paw Communications
        Using MailCat for Win32 Release Vs 2.6.1.1, on October 18, 1997, in 
Win95
4.0
        http://www.blackpaw.com/