ASP.Net MVC 4 + OAuth 1.0 - oauth_callback Not Sent

I need to authenticate with an OAuth 1.0 service.  I'm using the OAuthWebSecurity object to register my custom client in the AuthConfig.cs file.  

The request to retrieve temporary credentials is expecting the parameter "oauth_callback" to be sent in the querystring.  However, I see no way to specify this and it's not sent with the request.

The following is my custom service provider.

public static readonly ServiceProviderDescription CustomServiceDescription
            = new ServiceProviderDescription
{
    AccessTokenEndpoint =
            new MessageReceivingEndpoint("https://testserver/oauth",
            HttpDeliveryMethods.GetRequest),
    RequestTokenEndpoint =
            new MessageReceivingEndpoint("https://testserver/oauth",
            HttpDeliveryMethods.GetRequest),
    UserAuthorizationEndpoint =
            new MessageReceivingEndpoint("https://testserver/oauth/OAutha",
            HttpDeliveryMethods.GetRequest),
    TamperProtectionElements =
            new ITamperProtectionChannelBindingElement[] { new PlaintextSigningBindingElement()},
    ProtocolVersion = ProtocolVersion.V10,
};