I am working on this subject for whole day. Finally i did it. The keypoints
are;
1. Implement a class that is derived from
System.Web.Services.Protocols.SoapHttpClientProtocol (Similar to VS.NET
generated one but not it)
2. Add a string url address parameter to constructor and set this.Url member
variable.
3. There should be a method which should have same name with your web
service. use invoke to call your ws.
4. For additional security purposes u should use
System.Net.CredentialCache.DefaultCredentials

My code uses web services to transfer some secure data over SSL. There are
inner webservices whole are coordinated and managed by an asyncronous
webservice which is triggered by an asp page. This works with no loss. But
it cost me whole day programming... If it is not too necessary, my advice u
to call webservice in a normal way. Does your webservice url change
frequently ? If not use dynamic web service binding which will allow u to
set web service URL with an XML based configuration file....