use Time::Local qw( timelocal );

my %month_num_by_name = (
   JAN => 1,
   FEB => 2,
   ...
);

my ($d, $m, $y) = split(/-/, $date);
$m = $month_num_by_name{$m};

my $time = timelocal(0, 0, 0, $d, $m-1, $y);