It does work and is quite simple..
Using CS-Cart 1.3.4r2 as mentioned...
EDIT /skins/youskin..../admin/order_pages/order_details.tpl
Add the lines highlighted in RED :
{include file="common_templates/subheader.tpl" title=$lang.products_information}
<table cellpadding="2" cellspacing="1" border="0" width="100%">
<tr>
[COLOR=red] <td width="10%" class="manage-header"> {$lang.product_code}</td>
[/COLOR]<td class="manage-header"> {$lang.product}</td>
<td class="manage-header"> {$lang.options}</td>
<td width="5%" class="manage-header" align="center"> {$lang.price}</td>
<td width="5%" class="manage-header" align="center"> {$lang.amount}</td>
{if $order_info.use_discount}
and then :
{elseif $settings.Modules.product_configurator != 'Y' || !$oi.extra.in_configuration}
<tr {cycle values="class='manage-row', "}>
[COLOR=red]<td class="side-padding" height="22">{$oi.product_code}</td>[/COLOR]
<td class="side-padding" height="22">
<a href="{$index_script}?{$target_name}=products&{$mode_name}=update&product_id={$oi.product_id}" class="manage-root-item">{$oi.product|escape:html}</a>
{if $oi.extra.is_edp && $oi.extra.ekey}
{assign var="edp_exist" value="Y"}
<input type="hidden" name="prolongate_data[{$oi.product_id}][ekey]" value="{$oi.extra.ekey}" />
<table cellpadding="0" cellspacing="0" width="100%">
<tr>
I added extra code so it was easy for you to find...
I know this works 100% as ive been using it since I went live.