No arquivo web.sitemap:
<siteMap enableLocalization="true">
E então, basta utilizar as strings de tradução dessa maneira: $resources:<Name of resource file> ,<String>
Exemplos:
<siteMapNode title="$resources:Resource,Configuration" _permissionRequired="Customers" ImageCollapsed="administration.gif" ImageHoverCollapsed="administration_hover.gif" ImageExpanded="administration_hover.gif" >
<siteMapNode url="" title="$resources:Resource,LocalConfiguration">
<siteMapNode url="~/InfoControl/CompanyConfiguration.aspx" _permissionRequired="CompanyConfiguration" title="$resources:Resource,HeaderAndFooter" description="" ImageCollapsed="blank.gif" />