OAuth2 External Authentification

My webite (application) used  Asp.net Identity 2 beta  store user accounts.  I'm using VS2013  and Framework 4.5.1.   I want to let other website's users  can login my application  so my webiste's user account can raise.  the server  webiste can provie OAuth2 API service   and I have get the  appId and  appSecret.  My problem is  : Startup.Auth.cs  only have     MicrosoftAccountAuthentication、TwitterAuthentication、FacebookAuthentication 、GoogleAuthentication . etc  external login Like this:

app.UseExternalSignInCookie(DefaultAuthenticationTypes.ExternalCookie);

            // Uncomment the following lines to enable logging in with third party login providers
            //app.UseMicrosoftAccountAuthentication(
            //    clientId: "",
            //    clientSecret: "");

            //app.UseTwitterAuthentication(
            //   consumerKey: "",
            //   consumerSecret: "");

            //app.UseFacebookAuthentication(
            //   appId: "",
            //   appSecret: "");

            //app.UseGoogleAuthentication();

  How  I can implement  other external login?