Are these commands you have created yourself, or from a third party?
If you're attempting to control an ingame menu system, the keypresses (assuming this menu is controlled using the keyboard) your VoiceAttack command needs to produce would be identical to those you would input using your physical keyboard.
That is unless the layout of the menu is not consistent (E.G. it changes depending on one or more ingame states, like the location of your aircraft), in which case you would likely need to get data from the game to compensate for that (assuming relevant data is made available by the game, and you have a method for bringing it into VoiceAttack, E.G. using a plugin or inline function).