see http://bertcraven.wordpress.com/2011/03/27/implementing-a-rest-ful-service-using-openrasta-and-oauth-wrap-with-windows-azure-appfabric-acs/

Extensions.cs

namespace AzureClaimsAuthenticator
{
	using OpenRasta.Authentication;
	using OpenRasta.Configuration;
	using OpenRasta.Configuration.Fluent;
	using OpenRasta.DI;
	using OpenRasta.OperationModel.Interceptors;
	using OpenRasta.Pipeline.Contributors;

	public static class Extensions
	{
		public static void AzureClaimsAuthenticationScheme(this IUses anchor)
		{
			anchor.PipelineContributor<AuthenticationContributor>();
			anchor.CustomDependency<IAuthenticationScheme, AzureClaimsAuthenticationScheme>(DependencyLifetime.Singleton);
			anchor.CustomDependency<IOperationInterceptor, ClaimsAuthorizingInterceptor>(DependencyLifetime.Singleton);
		}

	}
}