Let's say it OUGHT to work! The place to do it is quite easy to find, and it does give you the option to add the delays, 2sec, 5sec, etc, and then add the HDMI command.
However, that's the way I tried with my DVD recorder, and in practice it was unreliable, so I now use the method that I mentioned and jlet explained, of allocating the command to a key in the activity, and sending it manually when the TV is ready to accept it!