Some cell phone alarms are more annoying than others, but all cell phone alarms are very annoying when they go off. Especially when they go off at about 3:15 in the morning when you had no plans to be awake that early.
You know what else is annoying? When a cell phone alarm goes off in the middle of an important meeting.
I think you get the gist of how this prank is supposed to work. Set the cell phone alarm to go off at a very annoying time.
It's pretty easy to set up the alarm on most phones, but if you cannot figure it out the alarm, then we have a solution. Just dial 611 and get the cell phone company operator to tell you how to set the alarm on that model cell phone. They will want your name and phone number and social security information, but just cut them off and ask to figure out how to do the alarm thingy. Most companies like Cingular, T-Mobile, or Verizon will be happy to help you with that.
Now if you want to be a real jerk, set the scheduling software to have the alarm go off at 3:45 in the morning several weeks from now. This will better cover your tracks.