depending on the charting sw you use, several indicators have been written for bar
timing, not sure how many also have audible alarms or if a specific time can be set
for an audible to go off
try http://www.timeleft.info/
"TimeLeft is a versatile desktop utility - it can be used as a countdown clock,
reminder, clock, alarm clock, tray clock, stopwatch, timer, sticker, auction watch,
work days/hours countdown clock and time synchronization utility."