What exactly? The Locale changes at runtime? Possibly not, as the Eclipse Translation Pattern is based on the dynamic injections. The pattern itself simply says that you move the translation mechanism to a separate method that is called via dynamic injection. So you could try to trigger it manually too if you know that the Locale changed. The question you need to answer on that is, how to get informed that the Locale has changed? The mechanism itself is listening to dynamic changes of the Locale in the context, while the pattern listens for dynamic injections of the Messages instances.
The new message extension itself is an OSGi service. Well two services to be more precise. The TranslationObjectSupplier which is an ExtendedObjectSupplier to get the @Translation annotation to work in conjunction with the IMessageFactoryService, which is an OSGi service that creates the Messages instance and fills the values dependent on the current set Locale. But you need the BundleLocalization object to get it working. If you can grab that from the registry aswell (it is also an OSGi service) than it should be possible to use the mechanism also in an 3.x application. Surely with some more pain than in an 4.x application. But that is true for almost every use case. ;-)
