Hi Raymond,
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.
Daniel
#CentraSite#API-Management#webMethods