I also tried it with Entity1 rather than the plural. (basing it one the NavigationMenu.plist. I am not 100% clear on the association between this and the rule file.
Anyway, apparently there is also an ERXNavigationManager.localizeDisplayKeys=true that I needed to set in Properties. NOW the tabs appear.
1. Created a new framework (for your custom version of the default skin)
2. Copy the WSR from ERModernDefaultSkin into the new skin framework.
3. Add er.modern.look.skinframework = MySkin to the skin's Properties file in resources
4. Copy the d2w.d2wmodel file from the default skin into the new skin's resources folder
5. Add the skin to the project.
If based on ERModernMoviesDemo:
6. Copy the user.d2wmodel file from ERModernMoviesDemo into the app's resources (modifying it so it displayed the proper entities instead of movies)
7. Copy the Session, DirectAction and Application contents from ERModernMoviesDemo into my app (making appropriate changes to the package etc)
8. Copy the contents of PageWrapper into my own PageWrapper (and changed the rule to have pageWrapperName point to the new wrapper) - including wod and html
9. If you want copy the MenuHeader or I replace the MenuHeader in the wrapper with the ERXNavigationMenu and add the navigationContext method from the MenuHeader class in ERModernMoviesDemo
10. Copy the NavigationMenu.plist from ERModernMoviesDemo into mine, and changed the entities appropriately
11. Copy the English.lproj folder from ERModernMoviesDemo to the new project and edit the Localizable.strings to display the proper information from the NavigationMenu.plist
This seems to have worked for me..... so far.