Register both the type and the handler and add an interceptor with a PolicyInjectionBehavior.
var container = new UnityContainer();
container.AddNewExtension<Interception>()
.RegisterType<TesCallHandler>()
.RegisterType<IFoo, Foo>(new Interceptor<TransparentProxyInterceptor>(),
new InterceptionBehavior<PolicyInjectionBehavior>())
.Configure<Interception>()
.AddPolicy("TestPolicy")
.AddCallHandler(new TestCallHandler());
var foo = container.Resolve<IFoo>();
foo.Test();