install4j cannot enumerate all users for you, this is generally a difficult problem because users are not always local and you might end up with a huge number of potential users.
I would recommend to create the configuration files the first time a user starts your application. You can add a custom installer application that contains a "Copy file or directories" action that can be invoked from your own code. Select the custom installer application on the Installer->Screens & Actions tab, then activate the "Launcher integration" tab on the right side. The integration wizard will give you a code snippet.