OK, so I am going to answer my own question …
I found this HOWTO on “Generating X.509 Certificates” which is located at:
http://www.ipsec-howto.org/x507.html
Beware, for some reason it says 507 in the URL, not 509.
Anyway, in OSX 10.3 the path to the OpenSSL library is
/System/Library/OpenSSL
and the CA.pl script meantion in the above HOWTO is at
/System/Library/OpenSSL/misc/CA.pl
However, before you can generate the certificate, you must first generate a private key. I’ll post again with instructions for that later on.
rgds
benjk