Using mssoap30 and user authentication

Hi,

I've written an Excel AddIn - originally for Excel 2007 but now using with Excel 2010.
It is used internally (work network) for accessing data from a SOAP server.
In fact there are two SOAP servers, one for read-only access and one for read-write access.
The read-write access is password protected but I am unable to find out how to include user authentication with the SOAP VB code.

The SOAP functions I have are modeled after this example, and are using the MS SOAP 3.0 Toolkit
http://www.soapuser.com/client4.html

Any help would be appreciated,
Thanks,

Brian