Yes, it would require that you localize the defaulttheme.jar by adding a
localized variant of the messages.properties file; adding to web.xml a context-param
for com.sun.rave.web.ui.theme.SUPPORTED_LOCALES and including
the variant(s) there. For working with the themes jar see the themes tutorial
http://developers.sun.com/prodtech/javatools/jscreator/learning/tutorials/2/the mes.html
And you might want to look at the Styles and Components tutorial as well.
/krys