You'll have to use the Bash command `systemsetup`
systemsetup Help Information
-------------------------------------
Usage: systemsetup -getdate
Display current date.
Usage: systemsetup -setdate <mm:dd:yy>
Set current date to <mm:dd:yy>.
Usage: systemsetup -gettime
Display current time.
Usage: systemsetup -settime <hh:mm:ss>
Set current time to <hh:mm:ss>.
Usage: systemsetup -gettimezone
Display current time zone.
Usage: systemsetup -settimezone <timezone>
Set current time zone to <timezone>. Use "-listtimezones" to list time zones.
If you read through this thread at the Adobe forums, then you'll see some examples of AppleScript. Because the command needs an administrator's password (sudo access), you'll probably have to do something like:
set _month to 12
set _day to 12
set _year to 12
set myScript to "systemsetup setdate " & _month & ":" & _day & ":" & _year
do shell script myScript with Administrator privileges
Obviously, you'll want to set the variables dynamically because that script will just set your system date to 12 Dec 2012. But, I haven't tested it, and screwing around my the date on my system is going to make so many programs throw so many fits that I don't really want to test it, so I leave you here on your own.
