I am not a UCCX person, and perhaps there are other easier methods.
How about something like this? When a call arrives, you do a DB lookup. If the emergency flag is set, follow path A and play the prompts specified by that path. If the emergency flag is not set, follow path B and play the prompts specified by that path.
Build a simple .NET Web Service that authenticates the user and allows authenticated users to change the state of the emergency flag, written to the database.
Regards,
Geoff