It looks like you found a solution but to address your original question of how to get messages out of the message source from any of the controller classes in Spring, they basically have to be made aware of their application context. This is done by implementing the ApplicationContextAware interface which the ApplicationObjectSupport class does. This class is a extended by all the controllers in spring so they are all aware of the application context. The ApplicationObjectSupport exposes the message source accessor via the application context with a get method.
A simple message could be retrievd from the message source like so
String foo = getMessageSourceAccessor().getMessage(msgKey, locale);