What you want to do is not use a standard hash, but instead use the Tie::IxHash OO methodology. It's not as clean, but it'll do what you want.

#!/usr/local/bin/perl -w
use strict;
use Tie::IxHash;

my $h = fooFunc();

print "This order now matches fooFunc()\n\n";

print $h->FETCH($_)."\n" for $h->Keys;

print "\n";

sub fooFunc {

    my $h = Tie::IxHash->new('donald' => 'duck');

    $h->Push('calvin' => 'human');
    $h->Push('hobbes' => 'tiger');
    $h->Push('mickey' => 'mouse');
    $h->Push('zorak'  => 'bug');

    return $h;
}
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Review the perldoc for Tie::IxHash for more info.