SirDice is right, the SE_SYSTEMTIME_NAME privilege in windows is disabled by default for most users. But I'm guessing that if you check out more about how the time in windows is controled you could come up with a solution.

Here are some pages that may help you get started. (this is for windows)

Setting the system time
http://msdn.microsoft.com/library/de...systemtime.asp

Access Control
http://msdn.microsoft.com/library/de...ss_control.asp