I can try adding the command sequence to the beginning of my Watch TV activity, and just start with that activity every time. It is not a very elegant solution, and wouldn't allow me to start with a different activity, but I think I am running out of options. It sounds like I cant map the command sequence to a key press, and just press it once no matter the activity I start with, so this may be my only option.

I have considered cutting the internal speaker wires, but it is wall mounted, heavy, and doesnt look like the speakers are easily accessed, so I ruled it out.