package CountingMetaClass;
use Moose;

extends 'Moose::Meta::Class';

has 'count' => (
    is      => 'rw', 
    isa     => 'Int', 
    default => sub { 0 }
);

after 'construct_instance' => sub {
    my $class = shift;
    $class->count($class->count + 1);
};

##</code><code>##

package Foo;
use metaclass ('CountingMetaClass'); # tell it what meta you want used first ...
use Moose;