When I'm making asmx web service calls from Silverlight, is there any way to have the (generated) SoapClient objects modify the address that they call the service on?

Specifically, I'd like to tack on a QueryString value onto each call that the service makes. So if I have

DataService.SilverlightServiceSoapClient C = new DataService.SilverlightServiceSoapClient();

Is there any way to do something like:

C.Address += "?Foo=Bar";

Which would allow me to, from my WebMethod, say:

HttpContext.Current.Request.QueryString["foo"];

Obviously I can modify my WebMethods to take this value in as a parameter, but I'd like to avoid doing that if possible.