package Maker;

sub make {
    my $pkg = caller;
    my $sub = sub {
        my $self = shift;
        print "w00t\n";
        $self->SUPER::go;
    };

    no strict 'refs';
    *{ $pkg . '::go' } = $sub;
}

##</code><code>##

package Foo;

sub go { print 42; }

package Bar;

use base 'Foo';

sub new { return bless { }, $_[0] }

Maker->make;

##</code><code>##

package main;

my $o = Bar->new;
$o->go;

##</code><code>##

w00t
Can't locate object method "go" via package "Maker" at mm.pl line 11.