You can provide the endpoint config in the following manner:
endpoint_config={"production_endpoints":{"url":"http://localhost:9763/services/HelloService?wsdl","config":null},"wsdlendpointService":"http://localhost:9763/services/HelloService","wsdlendpointPort":"http://localhost:9763/services/HelloService.HelloServiceHttpSoap11Endpoint","endpoint_type":"wsdl"}
Basically you need to provide the WSDL, Service URL and the port type as a JSON.
When do you mean configuring Basic Authentication are you trying to access a Backend Secured with Basic Authentication or are you trying to secure the API using Basic Authentication?