Generate config file from existing certificate?

[Joshua Bowman]

As the subject asks, is there any way to generate a config file from an
existing certificate? Either built into openssl or via third-party tool.
I'm having a lot of trouble getting the syntax right for some extensions
that use LDAP URIs, and I haven't found a good answer (but many questions
and misguided answers) on making it work. I thought the easiest way of all
would be to generate the config directly from a cert that already has all
of the extensions, then I can just modify as needed.