The fastest way: start indesign pressing down ctrl+alt+shift. But this way all your presets and other customizations are going to be deleted too.
The other way: use menuItems.add(associatedMenuAction, at, reference) on app.menus.item('Main').submenus.item('File')
associated menuaction is app.menuActions.item('Save') (or Save As...)
at should be LocationOptions.AFTER
and for reference: app.menus.item('Main').submenus.item('File').menuItems.item('Close')
In case of CS3; I don't know about the scripting of other versions.