Are there things that I did not try which would have been likely to succeed.

Not really :) but see next part

Is there a way to use that reference directly with Tie::Hash::Regex without making the copy?

Its not really important :) but see next part

#!/usr/bin/perl --
use strict; use warnings;
use Tie::Hash::Regex;
Main( @ARGV );
exit( 0 );
sub Tie::Hash::Regex::TIEHASH {
    my( $class, $ref ) = @_;
    $ref ||= {};
    return bless $ref, $class;
}
sub Main {
    my $sing = bless setSome(), 'Tie::Hash::Regex';
    my %song; tie %song, 'Tie::Hash::Regex', setSome();
    print $sing->FETCH(qr/pe/i), "\n";
    print $song{qr/by/i}, "\n";
#~     typeSome( \%song );
#~     typeSome( $sing );
}
sub setSome {
    my( $song ) = @_;;
    $song ||= {};
    $song->{Peter} = "I Am Peter, Hear Me Roar";
    $song->{Byrne} = "When I have nothing to say, my lips are sealed."
+;
    $song;
}
sub typeSome {
    my( $song ) = @_;
    while( my( $writer, $song ) = each %$song ){
        print "$writer: $song\n";
    }
}
__END__
[download]

And this is the point you should consider perlobj :)