Ignore voice commands / Speech Recognition Server timeout

Question

I'm fairly new to AppleScript but I've found it really entertaining and gloriously simple to pick up so far.  I've been using it mostly to make my own speakable items for the Mac's voice control, and I've managed to write some basic things like voice commands to set/change volume and brightness.  My goal at this point is to be able to do the majority of things I want to do on my computer by voice only.  Sue me - I just rewatched Iron Man and I really wish I had a JARVIS system right now. 
This means that the computer must always be listening for commands (I have set it to 'listen continuously with keyword', and set the keyword as 'optional before commands').  It defeats the purpose if I have to walk over and hit a key to start listening for commands.  At the same time, I don't want to have to speak a keyword, because I will invariably forget to do so and it's also an added hassle (especially when I have several commands to say - I don't want to have to say the keyword before each command). 
You might have an idea of where this is going.  Obviously, if the computer is always listening, it will pick up on normal conversation and try to interpret it. 
I could just deactivate voice commands when I'm not using it, but as I said earlier, I don't want to have to either hit a key or say a keyword.  In other words, I want to be able to activate and deactivate voice commands by voice.  Deactivating is easy.  Activating is what presents an interesting problem, because if it's deactivated, how will it hear my reactivation command? 
Thus, the first part of my question: is there a way - any way at all - to get voice commands to ignore commands until given some keyword, short of literally changing its settings to listen for a keyword before the command? 
I decided to try to use speech recognition.  This must, I think, be involved in some way, because as I said earlier, this presents the unique problem of having voice commands deactivated yet still able to recognise the reactivation command.  I had noticed that while the computer is listening for a specific command, it ignores anything that isn't what it is listening for.  I tried to use this to my advantage and wrote a script to listen for a reactivation command; until the reactivation command was given, the computer would ignore everything else.  The problem is that the speech recognition server times out after two minutes.  I have tried to increase this, but to no avail (see below for my attempts). 
Thus, the second part of my question: assuming there is no other answer to my first question, is there a way to get speech recognition to listen indefinitely?
Here are the two things I tried to make the timeout last longer, specifically for five minutes (300 seconds) in both cases.  Neither worked; both timed out after 120 seconds. 
tell application "SpeechRecognitionServer"
        set userinput to listen for {"resume voice commands"} giving up after 300
end tell
and
with timeout of 300 seconds
          set userinput to listen for {"resume voice commands"}
end timeout

Answer 1

UPDATE: I have since come up with an alternate solution.  I created two speakable items, one for 'deactivation' and one for 'activation'.  The deactivation command uses UI scripting to set voice commands to 'keyword required' mode (i.e. the keyword is required before each command); the activation command simply sets it back to 'keyword optional' mode. 
I figure that as long as I choose a keyword that's unique enough that it (and things that sound like it) won't come up too often in conversation, the computer will ignore anything I say once I activate the keyword requirement.  Then, I only need to say the keyword once along with the reactivation command to bring it out of this 'ignore commands' state. 
In a way, this is actually better, because it allows me to continue to use voice commands if I really need to, as opposed to having to say the reactivation command to get my computer to listen to me, saying my intended command, and then saying the deactivation command to make it ignore me again. 
All the same, if anyone has answers to any of my two original questions, please don't hesitate to share your knowledge!  It might come in handy later!