The second problem I had with CXF (or, more correctly, JAXB) was in trying to serialise JAXB objects such as CreateVolumeType into XML using a copy of JAXBuddy from Typica.
This failed with the error message: "Unable to marshal type XXX as an element because it is missing an @XmlRootElement annotation". Searching for this error message led me to this blog post by Kohsuke Kawaguchi, and so I copied the sample configuration from the comment into my binding file. This didn't work, and the error message remained the same - the configuration didn't take effect.
Googling again I found this CXF bug on serialisation and "simple" mode. The information in this issue, combined with the information in the wsdl-to-java documentation gave me the information I needed to correct the binding file.
As a humorous side-effect this also changed a lot of class names and broke a lot of code, but the new class-names are an improvement, so there we go.
My updated sample binding file is on pastebin here. Also, my original post about CXF is messed up in some way and I'll get round to fixing it soon.