Extend the localization substitution for "Cancel" and "OK" label in Prompt or the like

In bxml file, for example:

<bxml:define>
<Prompt bxml:id="confirmCloseTabPrompt" title="%ConfirmCloseTab"
message="%Reallyclosethistab"
options="['Cancel', 'OK']" selectedOptionIndex="1"/>
</bxml:define>

where all other string I can use % for substitution, except the Cancel and OK.