configuring timezones

[Pedro Zorzenon Neto]

Hi, all

  In my country (Brazil), each year there is a diferent day for changing the
clock to daylight saving time.

  This year, the clock changed in the wrong day from BRT (GMT - 3hs) to BRST 
(GMT - 2hs).

  How can I set the date that system will change my clock?

     Thanks
     Pedro