Here is another approach using the Hash::Flatten module:

#! perl
use strict;
use warnings;
use Hash::Flatten 'flatten';

my %meows =
(
    kittehs =>
    {
        purr    => 'happy',
        hiss    => 'mad',
        weather =>
        {
            tailflic => 'rain',
            shaking  => 'a doosy',
        },
    },
);

my $flat_meows = flatten(\%meows);
my @keys       = qw(kittehs weather tailflic);
my $new_key    = join '.', @keys;

printf "\$meows{%s} = %s\n", $new_key, $flat_meows->{$new_key};
[download]

Output:

18:26 >perl 831_SoPW.pl
$meows{kittehs.weather.tailflic} = rain

18:26 >
[download]

Hope that helps,