You need to:
1. create a logic_hook process_record containing something like that:
PHP Code:
$additional_details = "
<span id='adspan_{$relationship_addons_fields['ID']}' onmouseover=\"return SUGAR.util.getAdditionalDetails('RelationshipAddons', '{$relationship_addons_fields['ID']}', 'adspan_{$relationship_addons_fields['ID']}')\" >
<img class='more_detail' border='0' src='themes/Spectrum/images/MoreDetail.png' width='8' height='7'>
</span>";
$relationship_addons_fields['DESCRIPTION'] = $additional_details . $relationship_addons_fields['DESCRIPTION'];
Obviously you need to modify this code according to your needs;
Sugar try to retrieve either custom/modules/<ModuleName>/metadata/additionalDetails.php or modules/<ModuleName>/metadata/additionalDetails.php in order to display the DIV, so as Leads has such file on modules/<ModuleName>/metadata/additionalDetails.php you should need to create the custom one.
Cheers
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