I have used the "Microsoft Office 2003 Web Services Toolkit 2.01" toolkit (available here) on a few projects. It worked pretty well for me, although I also wrote the web services it was talking to, so I had the luxury of being able to fiddle with both ends of the process when getting it to actually work. :)
In fact, I just upgraded one of those apps from Access_2003 to Access_2010 and the SOAP client part of the app continued to work without modification. However, I did encounter one wrinkle during pre-deployment testing:
My app would not compile on a 64-bit machine running 32-bit Office_2010 because it did not like the early binding of the SoapClient30
object. When I switched to using late binding for that object the code would compile, but it did not work. So, for that particular app I had to add a restriction that 64-bit machines needed to be running 64-bit Office.
Also, be aware that Microsoft's official position is that "All SOAP Toolkits have been replaced by the Microsoft .NET Framework." (ref. here).