UsersController.cs

public class UsersController : ApplicationController // base class exposes profiler, etc.
{
    [Authorize(Roles = Roles.Administrator)]
    [Authorize(Roles = Roles.Owner)]
    public ActionResult Register()
    {
        return View();
    }

    [HttpPost]
    [Authorize(Roles = Roles.Administrator)]
    [IHandleRequestsFor(Roles.Administrator)]
    public ActionResult Register(UserRegistrationViewModel viewModel)
    {
        if(ModelState.IsValid)
        {
            var command = Mapper.Map<RegisterUserCommand>(viewModel);
            Bus.Send(command);
            
            return ViewForRole("Register_Complete"); // returns Register_Complete_Administrator
        }

        return View(viewModel);
    }

    [HttpPost]
    [Authorize(Roles = Roles.Owner)]
    [IHandleRequestsFor(Roles.Owner)]
    public ActionResult Register(UserRegistrationViewModel viewModel)
    {
        if(ModelState.IsValid)
        {
            viewModel.Account = // get account identifier for current user
            viewModel.Role = Roles.Employee; // well defined business scenario

            var command = Mapper.Map<RegisterUserCommand>(viewModel);
            Bus.Send(command);

            return ViewForRole("Register_Complete"); // returns Register_Complete_Owner
        }

        return View(viewModel);
    }
}