Please try this example:
Linvi
privatestatic IOAuthCredentials CredentialsCreator_WithCaptcha_SingleStep(string consumerKey, string consumerSecret) { Func<string, string> retrieveCaptcha = url => { // Change to display the information within your application Console.WriteLine("Go on : {0}", url); Console.WriteLine("Enter the captch : "); return Console.ReadLine(); }; var newCredentials = CredentialsCreator.GetCredentialsFromCaptcha(retrieveCaptcha, consumerKey, consumerSecret); Console.WriteLine("Access Token = {0}", newCredentials.AccessToken); Console.WriteLine("Access Token Secret = {0}", newCredentials.AccessTokenSecret); return newCredentials; }