To select a particular format you can use command such as this:
Set CONTENTFORMAT="Music"I don't think there's a command to switch to "none" or "disabled", though.
You can give the Content-Type drop-down a hotkey, in which case you can push the hotkey and then use up/down to cycle through the modes (including none and disabled), though it's a bit clunky.
I suspect you don't really need this at all if it's tied to your other thread as you can do that stuff without using content type formats.