Here's are three articles that talk about developing and using Web Services for "pre-.NET" applications (e.g. a VB6 app or MFC COM control).  Thanks to Brian Combs from PSS for forwarding to me:

1.  Integrating Web Services and COM Components using the SOAP Toolkit - Article

2.  Migrating from the Microsoft SOAP Toolkit to the .NET Framework - Article

3.  Calling .NET Assemblies and Web Services from VB6 - Article