$hashREF->{$key0}->{$key1}->{$key2} = $hashVAL

##</code><code>##

my $list = [ "k0", "k1", "k2", ];
my ($h,$t);
foreach my $k ( @$list ) {
    $h->{$k} = {};
    $h = $h->{$k};
}
$h = $val;