Try what I just commited. Your going to need to read the 
hooks.php.dist file to see how to define your custom field types and 
you are going to still need to add the attribute names via whups' 
admin UI.

This looks like it is at least close to what was originally inteded 
here...but at the least, it gives us *working* hooks :)

sorry I forgot the add the types

  if (!function_exists('_whups_hook_get_attributes')) {
      function _whups_hook_get_attributes(&$type = null)
      {
          $attributes = array( array() );
          $attributes = array(
                               array('human_name' => 'Customer Nr.',
                                                          'id' => 
'customernr_id',
                                                      'type' => 'text',
                                                'required' => 'true',
                                                'readonly' =>  false,
                                                      'desc' => 
'Customer Number',
                                                  'params' => '' ),

                               array('human_name' => 'Separator',
                                                           'id' => 
'separator_id',
                                                       'type' => 'header',
                                                 'required' =>  true,
                                                'readonly' =>  true,
                                                      'desc'  => '',
                                                   'params' => '' ),
                                array('human_name' => 'Customer',
                                                            'id' => 
'customer_id',
                                                        'type' => 'enum',
                                                  'required' => true,
                                                 'readonly' => false,
                                                   'desc'     => null,
                                                 'params'   => 
array(array('1' => 'ABC Inc.',
                                                                       
                    '2' => 'XYZ Co.'))) );
          return $attributes;
      }
  }

Just to summerize some discussions on IRC...

The issue is that the only thing the hook does right now is to return 
the definition of the Horde_Form field. It does nothing to retrieve 
the value from the backend.  The driver code assumes that it does. 
Letting the driver try to retrieve it won't work (at least in current 
code) since, the sql driver joins the attributes_desc table in the 
query used to retrieve the attribute values...and attributes added via 
the hook will not have an entry in that table.  It *looks* like the 
intent of the hook was to be able to add form field types other than 
text . If that's the case, I guess we can work some magic somewhere 
and make sure that the attributes_desc entries get created...

Marko? Any thoughts/input?

I used, text, enum, and several others. Non did work.

And what type are you supplying? You're going to have to post the hook 
I think.

when defining an attributes through the hook 
_whups_hook_get_attributes as in the example the form is created 
properly displaying the fields to enter the information, but as soon 
as the ticket is shown an error occurs:

A fatal error has occurred
Nonexistant class "Horde_Form_Type_" for field type ""

[line 159 of /usr/share/php/Horde/Form.php]

Till yet, i've not added database fields for any attributes to the 
whups tables since i didn't know which id it needs to have and into 
which of the whups tables it needs to go.