Countdown Timer with User Input!

I might be a complete newbie at this, but I can’t seem to find a tutorial or anything on how to do what I’m trying to do.

Ultimately I want to create a countdown for a widget where the user can put in a date and the app will countdown to that date. But the trick is–how do I insert the user variables into the actionscript for the countdown?

The script for the countdown is like this:
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currentDate = new Date();
thisYear = currentDate.getFullYear();

eventDate = new Date(2009, 11, 25);
eventMillisecs = eventDate.getTime();

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But, I want to be able to pull in user variables for “eventDate = new Date(Year, Month, Day)” Is this possible and if so, how?