Converting Metadata with GeoCombine
At first inspection, it looks like this is a one-by-one kind of thing.
Use the interactive rails console:
in your shell, navigate to the GeoDiscovery directory and run rails console
You can then run operations like creating an ISO metadata object:
iso_metadata = GeoCombine::Iso19139.new('./tmp/opengeometadata/ISO_Metadata.xml')
The current XSLT in the UWM GeoCombine fork uses XML 2.0 features that are not supported by Nokogiri, and by extension, GeoCombine.