Questa e l'API e il tipo che ti serve:
codice:
Private Type SYSTEMTIME
    wYear As Integer
    wMonth As Integer
    wDayOfWeek As Integer
    wDay As Integer
    wHour As Integer
    wMinute As Integer
    wSecond As Integer
    wMilliseconds As Integer
End Type

Declare Function SetSystemTime Lib "kernel32" Alias "SetSystemTime" (lpSystemTime As SYSTEMTIME) As Long