Hello-
What do you have so far?
It is 100% possible to do and not too complicated. Essentially you build an IVR script which updates an XML document living in the document repository; this will be your 'toggler' script. The value could also live in an external database if you have Premium licenses. In your IVR script you can control authentication in a few ways depending on what you're looking for. Frequently this is hard coded in the script.
In the script that needs to check the value you can either have it read / parse that XML file directly or you can use a sub-flow to accomplish this if you will have multiple scripts / applications using the same logic.
Thanks,
DJ