Either way works fine, though I prefer not to have multiple packages in one file. But that's just a matter of style.

However, it seems to me that defining a derived class would be a more sensible approach. If you don't want to make an actual module, you can define the class inline with your script.

The following is untested but demonstrates the idea.

#!/usr/bin/perl

use strict;
use Tk;
use Tk::Label;
use Tk::HList;

package Rudif::Tk::HList;
@Rudif::Tk::HList::ISA = ( 'Tk::HList' );

sub addrow {
    my ( $self, $row, $text ) = @_;
    $self->add($row);
    $self->itemCreate( $row, 0, -text => $text );
}

sub updaterow {
    my ( $self, $row, $text ) = @_;
    $self->itemConfigure( $row, 0, -text => $text );
}

package main;

# your stuff here
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