Here are some instructions on setting up translation in XPages:
http://www-10.lotus.com/ldd/ddwiki.nsf/dx/UsingLocalizationOptions.htm
you can use this with a action. What happens is you will have a property file with strings, these will be translated and then the correct one will be used. something like:
<xp:eventHandler>
<xp:this.action>
<xp:actionGroup>
<xp:confirm>
<xp:this.message><![CDATA[#{javascript:
//where "strings" is a variable pointing to the resource bundle
strings.getString("confirm.message.delete");
}]]></xp:this.message>
</xp:confirm>
... delete code ...
</xp:actionGroup>
</xp:this.action>
</xp:eventHandler>