How can I use the colorpicker for a form element?

Hmmm okay so I've just seen that you've actually contributed modules so you're not quite the slacker I assumed you are ;o)

Take a look at this which I've written for my own Tablemanager module;

tablemanager.css.inc

function tablemanager_css_styling($form_state) {
  $palette = array('thead' => '#ffffff', 'th.active' => '#ffffff', 'tr.even' => '#ffffff', 'tr.odd' => '#ffffff', 'td.active'  => '#ffffff');
  $names['colors'] = array(
    'thead' => t('thead'),
    'th.active' => t('th (active column)'),
    'tr.even' => t('even rows'),
    'tr.odd' => t('odd rows'),
    'td.active' => t('active column'),
  );
  $form['palette']['#tree'] = true;
  foreach ($palette as $name => $value) {
    $form['palette'][$name] = array(
      '#type' => 'textfield',
      '#title' => $names['colors'][$name],
      '#default_value' => $value,
      '#size' => 8,
    );
  }
  return $form;
} // tablemanager_css_styling

function theme_tablemanager_css_styling($form) {
  // Add Farbtastic color picker
  drupal_add_css('misc/farbtastic/farbtastic.css');
  drupal_add_js('misc/farbtastic/farbtastic.js');
  // Add our own js and css
  drupal_add_js(drupal_get_path('module', 'tablemanager') .'/misc/tablemanager.js');
  drupal_add_css(drupal_get_path('module', 'tablemanager') .'/misc/tablemanager_admin.css');

  // Palette
  $textfields = '<div id="palette" class="clear-block">';
  foreach (element_children($form['palette']) as $name) {
    $form['palette'][$name]['#attributes']['class'] = 'color_textfield';
    $form['palette'][$name]['#name'] = $name;
    $textfields .= drupal_render($form['palette'][$name]);
  }
  $textfields .= '</div>';

  $output .= theme('table', array(), array(array(array('data' => $textfields), array('data' => '<div class="colorpicker"></div>'), array('data' => tablemanager_example_table()))), array('id' => 'tablemanager-table-container'));

  // Render remaining fields
  $output .= drupal_render($form);
  return $output;
} // theme_tablemanager_css_styling

function tablemanager_example_table() {
  $header = array(array('data' => t('Name')), array('data' => t('Age'), 'field' => '2', 'sort' => 'asc'), array('data' => t('IQ')));
  $rows[] = array(array('data' => 'Peter'), array('data' => '35'), array('data' => '95'));
  $rows[] = array(array('data' => 'Lois'), array('data' => '30'), array('data' => '115'));
  $rows[] = array(array('data' => 'Paul'), array('data' => '33'), array('data' => '125'));
  return theme('table', $header, $rows, array('id' => 'tablemanager-example-table'));
} // tablemanager_example_table

tablemanager.js

// $Id$

// Global killswitch: only run if we are in a supported browser.
if (Drupal.jsEnabled) {
  $(document).ready(function () {
    // initiate farbtastic colorpicker
    var farb = $.farbtastic("div.colorpicker");
    $("input.color_textfield").each(function () {
      // set the background colors of all of the textfields appropriately
      $("table#tablemanager-example-table " + this.name).css("background-color", farb.color);
      farb.linkTo(this);
      // update the farbtastic colorpicker and example table when this textfield is clicked
      $(this).click(function () {
        $("table#tablemanager-example-table " + this.name).css("background-color", farb.color);
        farb.linkTo(this);
      });
    });
  });
}

Using code stolen completely from both the color module and the colorpicker module with absolutely no thought on my part. It's not finished as I'm doing other theme stuff with it, but it's a good starting point. If it doesn't work it's because I've removed parts of it I've added myself to simplify what you're looking at (and so I may have broken it, don't think so though?)

Pobster