Within CADLinkType there is GetExternalResourceReference (inherited from Element)
This returns a dictionary of GUID, ExternalResourceReference. There is usually just one entry for CADLinks but either way one of the entries will contain ExternalResourceReference.InSessionPath which will point to the path of the link.
Additionally there is ExternalResourceReference.GetReferenceInformation that will return a dictionary that will have an entry where the Key is 'Path' and the value is the path to the link: