importer is never called

It depends on how far the modules follow the common practices (look at their names). Try:

script.pl:

#!/usr/bin/perl
use warnings;
use strict;

use Ugly ();

puke('Where does it come from?');
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Ugly.pm:

package Ugly;

use warnings;
use strict;

my $package = (caller)[0];

sub puke {
    warn @_;
}

{   no strict 'refs';
    *{$package . '::puke'} = \&puke;
}

__PACKAGE__
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