Installation file for custom category field

mysql4-install-0.3.0.php

<?php

$installer = $this;
$installer->startSetup();

/**
 * This is an entity associated with catalog_category
 * @var  integer
 */
$entityTypeId     = $installer->getEntityTypeId('catalog_category');

/**
 * Use the default attribute set for catalog_category -- this refers to the table `eav_attribute_set`
 * In my case, it's 3, but this function should automatically get that for you.
 * @var integer
 */
$attributeSetId   = $installer->getDefaultAttributeSetId($entityTypeId);

/**
 * This determines what group (tab) that the field will be placed. "General Information" 
 * is the default tab, and I'm okay with this, but see `eav_attribute_group` for other
 * groups
 * @var integer
 */
$attributeGroupId = $installer->getDefaultAttributeGroupId($entityTypeId, $attributeSetId);

/**
 * Let's set up our attribute, customize the type as needed (e.g. int, varchar, decimal)
 * Note where I've used `internal_title` and change to your variable.
 */
$installer->addAttribute('catalog_category', 'internal_title',  array(
    'type'     => 'varchar', /* Type - see eav_entity_* for the different types */
    'label'    => 'Internal Title', /* Your label */
    'input'    => 'text', /* This refers to the type of form field should display*/
    'global'   => Mage_Catalog_Model_Resource_Eav_Attribute::SCOPE_STORE,
    'visible'           => TRUE,
    'required'          => FALSE,
    'user_defined'      => FALSE,
    'default'           => ''
));

/**
 * Now, add the attribute to the proper attribute group - again, replace the variable title
 * with yours.
 */
$installer->addAttributeToGroup(
    $entityTypeId,
    $attributeSetId,
    $attributeGroupId,
    'internal_title',
    '2' /* Refers to the sort order of fields - see `eav_entity_attribute` for reference on the location of other fields.  I want this right below the active field, so 2 works for me.*/
);

$installer->endSetup();