SP Create IdP Metadata

[Mark Neidig]

I am the SP.
Peter explained that "Step one[to configuring a new IdP] is always to acquire (or create) SAML metadata for both IDPs and add them to your SP via MetadataProviders."

The IdP is not Shibboleth. The admin for the IdP is not aware of SAML metadata files for his IdP let alone generating them. 

He provided his X509 cert and I've successfully installed it. 
I have an IdP metadata file for a different IdP that I can model.

How do I "create" the IdP metadata file as Peter suggested?

Thank you,
Mark