select/run test by test item using command line

There is a way you can do this currently. See this article here:

http://support.smartbear.com/viewarticle/54654/

Which can then be put into a console application as well to run as a scheduled task:

    class Program
    {
        static void Main(string[] args)
        {
            if (args.Length == 0)
            {
                Console.WriteLine("Expecting arguments");
                Console.Write("Press any key to continue...");
                Console.ReadLine();
            }
            else
            {
                string testItemGroup = "";
                string project = "";

                for (int i = 0; i < args.Length; i++)
                {
                  if (Regex.IsMatch(args[i], @"\/testitemgroup:", RegexOptions.IgnoreCase))
                  {
                      testItemGroup = Regex.Replace(args[i], @"\/testitemgroup:", "", RegexOptions.IgnoreCase);
                  }
                  if (Regex.IsMatch(args[i], @"\/p:", RegexOptions.IgnoreCase))
                  {
                      project = Regex.Replace(args[i], @"\/p:", "", RegexOptions.IgnoreCase);
                  }
                  if (Regex.IsMatch(args[i], @"\/project:", RegexOptions.IgnoreCase))
                  {
                      project = Regex.Replace(args[i], @"\/project:", "", RegexOptions.IgnoreCase);
                  }                
                }

                TestFunc(args[0], project, testItemGroup);
            }
            
        }

        private static void TestFunc(string projectSuite, string project, string testItemGroup)
        {
            const string TCProgID = "TestComplete.TestCompleteApplication.10";
            object TestCompleteObject = null;

            // Obtains access to TestComplete
            try
            {
                TestCompleteObject = Marshal.GetActiveObject(TCProgID);
            }
            catch
            {
                try
                {
                    TestCompleteObject = Activator.CreateInstance(Type.GetTypeFromProgID(TCProgID));
                }
                catch
                {
                }
            }

            if (TestCompleteObject == null) return;

            // Obtains ITestCompleteCOMManager 
            TestComplete.ITestCompleteCOMManager TestCompleteManager = (TestComplete.ITestCompleteCOMManager)TestCompleteObject;
            // Obtains Integration object
            TestComplete.ItcIntegration IntegrationObject = TestCompleteManager.Integration;

            // We have a reference to the integration object.
            // Now we can use its methods and properties to automate TestComplete.

            // Loads the project suite
            IntegrationObject.OpenProjectSuite(projectSuite);

            // Checks whether the project suite was opened
            // If the project suite cannot be opened, closes TestComplete
            if (!IntegrationObject.IsProjectSuiteOpened())
            {
                Console.WriteLine("Could not open the project suite.");
                // Closes TestComplete
                TestCompleteManager.Quit();
                // Releases COM objects
                Marshal.ReleaseComObject(IntegrationObject);
                Marshal.ReleaseComObject(TestCompleteManager);
                Marshal.ReleaseComObject(TestCompleteObject);
                return;
            }

            try
            {
                // Runs the test
                IntegrationObject.RunProjectTestItem(project, testItemGroup);

                // Waits until testing is over
                while (IntegrationObject.IsRunning())
                    Thread.Sleep(5000);

                // Check the results
                switch (IntegrationObject.GetLastResultDescription().Status)
                {
                    case TestComplete.TC_LOG_STATUS.lsOk:
                        Console.WriteLine("The test run finished successfully.");
                        break;
                    case TestComplete.TC_LOG_STATUS.lsWarning:
                        Console.WriteLine("Warning messages were posted to the test log.");
                        break;
                    case TestComplete.TC_LOG_STATUS.lsError:
                        Console.WriteLine("Error messages were posted to the test log.");
                        break;
                }
            }
            catch (System.Runtime.InteropServices.COMException ex)
            {
                Console.WriteLine("An exception occurred: " + ex.Message);
            }
            finally
            {
              
                // Closes TestComplete
                TestCompleteManager.Quit();
                // Releases COM objects
                Marshal.ReleaseComObject(IntegrationObject);
                Marshal.ReleaseComObject(TestCompleteManager);
                Marshal.ReleaseComObject(TestCompleteObject);
            }
        }
    }