Single-assembly multi-language Windows Forms deployment (ILMerge and satellite assemblies / localization) - possible?

The only way I can see this working is by creating a class that derives from ResourceManager and then overriding the InternalGetResourceSet and GetResourceFileName methods. From there, you should be able to override where resources are obtained, given a CultureInfo instance.

A different approach:

1) add your resource.DLLs as embededed resources in your project.

2) add an event handler for AppDomain.CurrentDomain.ResourceResolve This handler will fire when a resource cannot be found.

      internal static System.Reflection.Assembly CurrentDomain_ResourceResolve(object sender, ResolveEventArgs args)
            {
                try
                {
                    if (args.Name.StartsWith("your.resource.namespace"))
                    {
                        return LoadResourcesAssyFromResource(System.Threading.Thread.CurrentThread.CurrentUICulture, "name of your the resource that contains dll");
                    }
                    return null;
                }
                catch (Exception ex)
                {
                    return null;
                }
            }

3) Now you have to implement LoadResourceAssyFromResource something like

    private Assembly LoadResourceAssyFromResource( Culture culture, ResourceName resName)
            {
                        //var x = Assembly.GetExecutingAssembly().GetManifestResourceNames();

                        using (var stream = Assembly.GetExecutingAssembly().GetManifestResourceStream(resName))
                        {
                            if (stream == null)
                            {
                                //throw new Exception("Could not find resource: " + resourceName);
                                return null;
                            }

                            Byte[] assemblyData = new Byte[stream.Length];

                            stream.Read(assemblyData, 0, assemblyData.Length);

                            var ass = Assembly.Load(assemblyData);

                            return ass;
                        }
            }