sub put_element {
    my $current = \ $_[0];
    shift;
    my $value   = pop;

    $current = \ $$current->{ +shift } while @_;
    $$current = $value;
}

use Data::Dumper;
my %DATA;

put_element( $DATA{3}, 'h', 'i', "Worked" );  ## $DATA{3} autovifified too
put_element( $DATA{3}, 'b', 'y', 'e' );       ## $DATA{3} exists

print Dumper \%DATA;