string strAppPoolName = "MyAppPool";
string strUserName = Environment.UserDomainName + "\\" + "myappusername";
addUserAccount(strUserName, strUserPass);
using (ServerManager serverManager = new ServerManager())
{
    //Add application pool
    ApplicationPool appPool = serverManager.ApplicationPools.Add(strAppPoolName);
    appPool.AutoStart = true;
    appPool.ManagedPipelineMode = ManagedPipelineMode.Integrated;
    appPool.ManagedRuntimeVersion = "v4.0";
    appPool.ProcessModel.MaxProcesses = 1;
    //Assign identity to a custom user account
    appPool.ProcessModel.IdentityType = ProcessModelIdentityType.SpecificUser;
    appPool.ProcessModel.UserName = strUserName;
    appPool.ProcessModel.Password = strUserPass;
}

将用户添加到Active Directory的位置：

public static void addUserAccount(string sUserName, string sPassword)
{
    using (PrincipalContext oPrincipalContext = new PrincipalContext(ContextType.Domain))
    {
        using (UserPrincipal up = new UserPrincipal(oPrincipalContext))
        {
            up.SamAccountName = sUserName;
            up.SetPassword(sPassword);
            up.Enabled = true;
            up.PasswordNeverExpires = true;
            up.Description = "My app's user account";
            up.Save();
        }
    }
}

问题是，当我稍后将该站点和应用程序添加到该应用程序池下的IIS 7时，Web应用程序无法运行，因为它没有足够的权限。更重要的是，对于我来说，某些.NET类(例如System.Security.Cryptography)会因意外错误代码而失败，即使我手动将此新用户帐户的读/写权限设置为安装了我的Web应用程序的文件系统文件夹。