I just registered to say brilliant! ... and simple.

thanks a lot brandon! 

you saved my ass on this one, I was preparing to use the Spring's Struts Plugin , DelegatingActionProxy (refactoring all my actions, declaring them twice) and use AOP to control the injected mocks... not simple

I'd just add to the article that you have to replace your getBean(...) implementation with the ObjectFactory.getBean(...) one. 
Which is just changing one line if you have a BaseAction that all your Struts 1 action extends...