Data Connection: Web Service with HTTP Basic Authentication

Hi,

I am trying to add a data connection to a dashboard that calls a non-SAP web service.  The web service requires basic http authentication.  I can import the WSDL URL and map the input/output values for the web services' methods, but it is not clear to me how/where I should to add the username and password. Hopefully it is something simple.  Can someone please provide direction?

Thanks!