$ perl tuv.pl
$VAR1 = {
          'a' => {
                   'b' => {
                            'c' => 42
                          }
                 },
          'abc' => {
                     'def' => {
                                'ghi' => {
                                           'jkl' => {
                                                      'xyz' => 'value'
                                                    }
                                         }
                              }
                   },
          'shock' => 'jock',
          'x' => {
                   'y' => {
                            'z' => 69
                          }
                 }
        };

Roboticus@Waubli ~
$ cat tuv.pl
#!/usr/bin/env perl
use strict;
use warnings;
use Data::Dumper;

sub set_hash {
    my $hr = shift;
    my $val = shift;
    my $last_key = pop;
    while (@_) {
        my $key = shift;
        $hr->{$key} = {} if ! exists $hr->{$key};
        $hr = $hr->{$key};
    }
    $hr->{$last_key} = $val;
}


my %h;
set_hash(\%h, 42, 'a', 'b', 'c');
set_hash(\%h, 69, 'x', 'y', 'z');
set_hash(\%h, 'jock', 'shock');
set_hash(\%h, 'value', 'abc', 'def', 'ghi', 'jkl', 'xyz');
print Dumper(\%h);