A bit of refactoring to avoid duplication and readability.

Still needs to verify that this doesn't cause any regressions.

Main.cs

@@ -501,48 +501,27 @@ namespace winsw
                 args[0] = args[0].ToLower();
                 if (args[0] == "install")
                 {
+                    string username=null, password=null;
                     if (args.Count > 1 && args[1] == "/p") {
                         // we expected username/password on stdin
                         Console.Write("Username: ");
-                        string username = Console.ReadLine ();
+                        username = Console.ReadLine();
                         Console.Write("Password: ");
-                        StringBuilder password = new StringBuilder ();
-                        ConsoleKeyInfo key;
-                        while (true) {
-                            key = Console.ReadKey (true);
-                            if (key.Key == ConsoleKey.Enter) {
-                                break;
-                            } else if(key.Key == ConsoleKey.Backspace) {
-                                password.Remove (password.Length - 1, 1);
-                                Console.Write ("\b \b");
-                            } else {
-                                Console.Write ('*');
-                                password.Append (key.KeyChar);
-                            }
-                        }
-
-                        svc.Create (
-                            d.Id,
-                            d.Caption,
-                            "\"" + ServiceDescriptor.ExecutablePath + "\"",
-                            WMI.ServiceType.OwnProcess,
-                            ErrorControl.UserNotified,
-                            StartMode.Automatic,
-                            d.Interactive,
-                            username,
-                            password.ToString (),
-                            d.ServiceDependencies);
-                    } else {
-                        svc.Create (
-                            d.Id,
-                            d.Caption,
-                            "\"" + ServiceDescriptor.ExecutablePath + "\"",
-                            WMI.ServiceType.OwnProcess,
-                            ErrorControl.UserNotified,
-                            StartMode.Automatic,
-                            d.Interactive,
-                            d.ServiceDependencies);
+                        password = ReadPassword();
                     }
+
+                    svc.Create (
+                        d.Id,
+                        d.Caption,
+                        "\"" + ServiceDescriptor.ExecutablePath + "\"",
+                        WMI.ServiceType.OwnProcess,
+                        ErrorControl.UserNotified,
+                        StartMode.Automatic,
+                        d.Interactive,
+                        username,
+                        password,
+                        d.ServiceDependencies);
+
                     // update the description
                     /* Somehow this doesn't work, even though it doesn't report an error
                     Win32Service s = svc.Select(d.Id);
@@ -627,5 +606,30 @@ namespace winsw
             }
             ServiceBase.Run(new WrapperService());
         }
+
+        private static string ReadPassword()
+        {
+            StringBuilder buf = new StringBuilder();
+            ConsoleKeyInfo key;
+            while (true)
+            {
+                key = Console.ReadKey(true);
+                if (key.Key == ConsoleKey.Enter)
+                {
+                    return buf.ToString();
+                }
+                else if (key.Key == ConsoleKey.Backspace)
+                {
+                    buf.Remove(buf.Length - 1, 1);
+                    Console.Write("\b \b");
+                }
+                else
+                {
+                    Console.Write('*');
+                    buf.Append(key.KeyChar);
+                }
+            }
+        }
+
     }
 }

WmiSchema.cs

@@ -48,8 +48,6 @@ namespace WMI
     public interface Win32Services : IWmiCollection
     {
         // ReturnValue Create(bool desktopInteract, string displayName, int errorControl, string loadOrderGroup, string loadOrderGroupDependencies, string name, string pathName, string serviceDependencies, string serviceType, string startMode, string startName, string startPassword);
-        void Create(string name, string displayName, string pathName, ServiceType serviceType, ErrorControl errorControl, StartMode startMode, bool desktopInteract, string[] serviceDependencies);
-        
         void Create(string name, string displayName, string pathName, ServiceType serviceType, ErrorControl errorControl, StartMode startMode, bool desktopInteract, string startName, string startPassword, string[] serviceDependencies);
 
         Win32Service Select(string name);