Add web reference to visual studio from an xml

I have a project in Visual Studio where I make use of a client webservice through some web references that the client passed me before. Now the client wants to change this webservice, so I have to add the new web references. But the client tells me that the new wsdl is not available for security reasons, and gives me an XML with the definition of the new WSDL. How can I add the new web reference if the webservice URL is not published yet? Can I do it from that xml that you send me? Thanks.