How to pass a parameter along with h:commandButton

One of the most common approaches to change locale in JSF+Seam - with <h:selectOneMenu>:

<h:form  action="#{localeSelector.select}" rendered="false">
    <h:selectOneMenu value="#{localeSelector.language}" onchange="submit()">
        <f:selectItem itemLabel="English" itemValue="en" />
        <f:selectItem itemLabel="Francais" itemValue="fr" />
    </h:selectOneMenu>
</h:form>

I want to implement locale changes with buttons. So, the question is - how to pass the parameter (en, fr, etc.) to update the bean with <h:commandButton>? Maybe <h:inputHidden> would help?