Ok, so below is my SmartPost.php file now. Basically a flat rate clone with the addition of the selection of the parcel terminals. The small part I added is just before the function install() near the bottom of the file.

Now all I need is to store the customers selection and atm I have absolutely no idea how to go about it. If anyone could point out a similar solution used somewhere within Zen Cart, I could study that and possibly make this work.

Please, any help is greatly appreciated.

Code:
<?php
//
// +----------------------------------------------------------------------+
// |zen-cart Open Source E-commerce                                       |
// +----------------------------------------------------------------------+
// | Copyright (c) 2009 Rait Lotamõis                           |
// |                                                                      |
// | http://www.zen-cart.com/index.php                                    |
// |                                                                      |
// | Portions Copyright (c) 2003 osCommerce                               |
// +----------------------------------------------------------------------+
// | This source file is subject to version 2.0 of the GPL license,       |
// | that is bundled with this package in the file LICENSE, and is        |
// | available through the world-wide-web at the following url:           |
// | http://www.zen-cart.com/license/2_0.txt.                             |
// | If you did not receive a copy of the zen-cart license and are unable |
// | to obtain it through the world-wide-web, please send a note to       |
// | [email protected] so we can mail you a copy immediately.          |
// +----------------------------------------------------------------------+


  class SmartPost {
    var $code, $title, $description, $icon, $enabled;

// class constructor
    function SmartPost() {
      global $order, $db;

      $this->code = 'SmartPost';
      $this->title = MODULE_SHIPPING_SMARTPOST_TEXT_TITLE;
      $this->description = MODULE_SHIPPING_SMARTPOST_TEXT_DESCRIPTION;
      $this->sort_order = MODULE_SHIPPING_SMARTPOST_SORT_ORDER;
      $this->icon = '';
      $this->tax_class = MODULE_SHIPPING_SMARTPOST_TAX_CLASS;
      $this->tax_basis = MODULE_SHIPPING_SMARTPOST_TAX_BASIS;

      // disable only when entire cart is free shipping
      if (zen_get_shipping_enabled($this->code)) {
        $this->enabled = ((MODULE_SHIPPING_SMARTPOST_STATUS == 'True') ? true : false);
      }

      if ( ($this->enabled == true) && ((int)MODULE_SHIPPING_SMARTPOST_ZONE > 0) ) {
        $check_flag = false;
        $check = $db->Execute("select zone_id from " . TABLE_ZONES_TO_GEO_ZONES . " where geo_zone_id = '" . MODULE_SHIPPING_SMARTPOST_ZONE . "' and zone_country_id = '" . $order->delivery['country']['id'] . "' order by zone_id");
        while (!$check->EOF) {
          if ($check->fields['zone_id'] < 1) {
            $check_flag = true;
            break;
          } elseif ($check->fields['zone_id'] == $order->delivery['zone_id']) {
            $check_flag = true;
            break;
          }
	$check->MoveNext();
        }

        if ($check_flag == false) {
          $this->enabled = false;
        }
      }
    }

// class methods
    function quote($method = '') {
      global $order;
$this->generateSelect('smartpost');
      $this->quotes = array('id' => $this->code,
                            'module' => MODULE_SHIPPING_SMARTPOST_TEXT_TITLE,
                            'methods' => array(array('id' => $this->code,
                                                     'title' => MODULE_SHIPPING_SMARTPOST_TEXT_WAY,
                                                     'cost' => MODULE_SHIPPING_SMARTPOST_COST)));

      if ($this->tax_class > 0) {
        $this->quotes['tax'] = zen_get_tax_rate($this->tax_class, $order->delivery['country']['id'], $order->delivery['zone_id']);
      }

      if (zen_not_null($this->icon)) $this->quotes['icon'] = zen_image($this->icon, $this->title);

      return $this->quotes;
    }

    function check() {
      global $db;
      if (!isset($this->_check)) {
        $check_query = $db->Execute("select configuration_value from " . TABLE_CONFIGURATION . " where configuration_key = 'MODULE_SHIPPING_SMARTPOST_STATUS'");
        $this->_check = $check_query->RecordCount();

      }
      return $this->_check;
    }

// let's try and add the dropdown with locations next
    function generateSelect($name) {
	$arrSmartPostPlaces = unserialize(file_get_contents("http://www.smartpost.ee/places.php"));
	$html = '<select name="'.$name.'">';
	foreach ($arrSmartPostPlaces as $value) {
            		if ($value['active'] == 1) {
		$html .= '<option value='.$value['name'].'>'.htmlentities($value['name']).'</option>';
            		}
	}


	$html .= '</select>';
	return $html;
    }


    function install() {
      global $db;
      $db->Execute("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, set_function, date_added) values ('Enable SmartPost', 'MODULE_SHIPPING_SMARTPOST_STATUS', 'True', 'Do you want to offer SmartPost shipping?', '6', '0', 'zen_cfg_select_option(array(\'True\', \'False\'), ', now())");
      $db->Execute("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, date_added) values ('Shipping Cost', 'MODULE_SHIPPING_SMARTPOST_COST', '29.00', 'The shipping cost for all orders using this shipping method.', '6', '0', now())");
      $db->Execute("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, use_function, set_function, date_added) values ('Tax Class', 'MODULE_SHIPPING_SMARTPOST_TAX_CLASS', '0', 'Use the following tax class on the shipping fee.', '6', '0', 'zen_get_tax_class_title', 'zen_cfg_pull_down_tax_classes(', now())");
      $db->Execute("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, set_function, date_added) values ('Tax Basis', 'MODULE_SHIPPING_SMARTPOST_TAX_BASIS', 'Shipping', 'On what basis is Shipping Tax calculated. Options are<br />Shipping - Based on customers Shipping Address<br />Billing Based on customers Billing address<br />Store - Based on Store address if Billing/Shipping Zone equals Store zone', '6', '0', 'zen_cfg_select_option(array(\'Shipping\', \'Billing\', \'Store\'), ', now())");
      $db->Execute("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, use_function, set_function, date_added) values ('Shipping Zone', 'MODULE_SHIPPING_SMARTPOST_ZONE', '0', 'If a zone is selected, only enable this shipping method for that zone.', '6', '0', 'zen_get_zone_class_title', 'zen_cfg_pull_down_zone_classes(', now())");
      $db->Execute("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, date_added) values ('Sort Order', 'MODULE_SHIPPING_SMARTPOST_SORT_ORDER', '0', 'Sort order of display.', '6', '0', now())");
    }

    function remove() {
      global $db;
      $db->Execute("delete from " . TABLE_CONFIGURATION . " where configuration_key in ('" . implode("', '", $this->keys()) . "')");
    }

    function keys() {
      return array('MODULE_SHIPPING_SMARTPOST_LOCATION', 'MODULE_SHIPPING_SMARTPOST_STATUS', 'MODULE_SHIPPING_SMARTPOST_COST', 'MODULE_SHIPPING_SMARTPOST_TAX_CLASS', 'MODULE_SHIPPING_SMARTPOST_TAX_BASIS', 'MODULE_SHIPPING_SMARTPOST_ZONE', 'MODULE_SHIPPING_SMARTPOST_SORT_ORDER');
    }
  }
?>