This is topic covered in perllol. Using that reference, here's a sample script that does what you're looking to do.

use strict;
use Data::Dumper;

my @array;

push @{$array[0]},[0,1,2];

print Dumper @array;
[download]

Here's the output:

$VAR1 = [
          [
            0,
            1,
            2
          ]
        ];
[download]