you can register such artefacts in CentraSite by creating custom asset types. That way you can add attributes that you are interested in to manage and show to your users. The question would be how to load/extract metadata from your existing sources. But you can add custom importers that extract data you are interested in and publish it.
For MQ - There seems to a capability to create MQ Service Definitions in MQ Explorer which ends up in a WSDL. That should import into CentraSite just fine with the ootb importer.
So a custom type is required to be created then? I understand what you are saying regarding being able to define the attributes you want to make available. But this option is therefore only available in the full version of CentraSite (create custom type, create custom importer).
How would one utilize the CE version for non-webMethods services? (beyond those that could be imported as WSDLs)