Set up an alarm at X time of the game?

[ZunaSW]

Hello, sorry my english.
I want to set up an alarm when it is X time in the game (game time), for example, I want this alarm to be at 3:00 AM in the game. I don't really have idea of how to do it, I know there is not game time actually in the game, so I don't know if this is possible. I saw this library, but I don't know if it would do what I want, and if it does, how to do it: http://www.esoui.com/downloads/info53-AceTimer.html
Can anyone help me? : ) Thank you.