I've given up. The Axis2 Maven2 plugin does not seem to work correctly, so I've resorted to using the command-line tool, which does work. My command was:
wsdl2java.bat -d jaxbri -o
I used the JAXBRI output format because XMLBeans is basically dormant. Unfortunately the JAXBRI compiler generates sources in an "src" subdirectory, which can't be changed via command-line options, so some manual copy-and-pasting is required.
Secondly, the generated classes then depend on axis. So this needs to be added to the POM:
(Blogger broke my XML):
Thirdly, there's an undeclared dependency in Axis2-generated code on Axiom, so this also needs to be added:
(The latest version is 1.2.8, but this doesn't seem to be in repos yet.)
Following which, attempting to run this:
AmazonEC2Stub stub = new AmazonEC2Stub("http://eu-west-1.ec2.amazonaws.com");
DescribeRegionsType t = new DescribeRegionsType();
...rendered many different ClassNotFoundExceptionS which were, one after another, which I attempted to solve shotgun-style by adding each new dependency to the POM as it cropped up. This was an abject failure - I stopped at org.apache.axis2.transport.local.LocalTransportSender, which apparently is only available in Axis2 v. 1.2 (I'm using 1.5.1). So instead I deleted all the Axis2-related stuff from my POM and just added the JARs from the 1.5.1 downloded ZIP file straight to the Eclipse project.
This worked, and gave me the error message that I was looking for, to whit: "AWS was not able to authenticate the request: access credentials are missing". From here, I would just need to get the Rampart/WS-Security/WSS4J stuff working properly with the Amazon X.509 certificate, and then I should be home free. We shall see.
Further light reading can be found on this article on IBM developer works and this article on SOAP clients with Axis.
Update 2009/12/20: The work has been done (I should have googled first!), and it is herculean, as you can see by reading this impressive tutorial for creating an Axis2 SOAP Client for the Amazon Product Advertising API.