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You have to open the Automator app and then select iCal alarm. Then go to the iCal folder and select the iCalBirthdays file and drag it to the box on the right, then it will run. Enter all the parameters that you want (I noticed that you cannot change the name of the calendar, its doesnt work for some reason). Once you have entered in all you alarms, you run the program and you are done.

I hope that helps. I just figured it out. I noticed that it doesnt auto update though, meaning that if you add a new b-day in contacts, it doesnt add to iCal, you need to run the iCalBirthdays to update.
 
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