procedure TForm1.Button1Click(Sender: TObject);
var hFile: Cardinal; SystemTime: TSystemTime; CreationTime: TFileTime;
begin
if not OpenDialog1.Execute then Exit;
hFile := _lopen(PChar(OpenDialog1.FileName), OF_WRITE);
DateTimeToSystemTime(StrToDateTime('10/05/1983 0:0:0'), SystemTime);
SystemTimeToFileTime(SystemTime, CreationTime);
SetFileTime(hFile, @CreationTime, nil, nil);
CloseHandle(hFile);
end;