In order to reduce the file size, I removed the 4 picture files inside the original plugin. Please be kind! You can download it from here. Hope it helps for those of you who still need the multilingual version.

1. Make sure that you have already had the .htaccess file in your PrestaShop’s root directory, which has the content like the following:

   # .htaccess automaticaly generated by PrestaShop e-commerce open-source solution
   # http://www.prestashop.com - http://www.prestashop.com/forums
    
   # URL rewriting module activation
   RewriteEngine on
    
   # URL rewriting rules
   RewriteRule ^([a-z0-9]+)\-([a-z0-9]+)(\-[_a-zA-Z0-9-]*)/([_a-zA-Z0-9-]*)\.jpg$ /prestashop1250/img/p/$1-$2$3.jpg [L,E]
   RewriteRule ^([0-9]+)(\-[_a-zA-Z0-9-]*)/([_a-zA-Z0-9-]*)\.jpg$ /prestashop1250/img/c/$1$2.jpg [L,E]
   RewriteRule ^lang-([a-z]{2})/([a-zA-Z0-9-]*)/([0-9]+)\-([a-zA-Z0-9-]*)\.html(.*)$ /prestashop1250/product.php?id_product=$3&isolang=$1$5 [L,E]
   RewriteRule ^lang-([a-z]{2})/([0-9]+)\-([a-zA-Z0-9-]*)\.html(.*)$ /prestashop1250/product.php?id_product=$2&isolang=$1$4 [L,E]
   RewriteRule ^lang-([a-z]{2})/([0-9]+)\-([a-zA-Z0-9-]*)(.*)$ /prestashop1250/category.php?id_category=$2&isolang=$1 [QSA,L,E]
   RewriteRule ^([a-zA-Z0-9-]*)/([0-9]+)\-([a-zA-Z0-9-]*)\.html(.*)$ /prestashop1250/product.php?id_product=$2$4 [L,E]
   RewriteRule ^([0-9]+)\-([a-zA-Z0-9-]*)\.html(.*)$ /prestashop1250/product.php?id_product=$1$3 [L,E]
   RewriteRule ^([0-9]+)\-([a-zA-Z0-9-]*)(.*)$ /prestashop1250/category.php?id_category=$1 [QSA,L,E]
   RewriteRule ^content/([0-9]+)\-([a-zA-Z0-9-]*)(.*)$ /prestashop1250/cms.php?id_cms=$1 [QSA,L,E]
   RewriteRule ^([0-9]+)__([a-zA-Z0-9-]*)(.*)$ /prestashop1250/supplier.php?id_supplier=$1$3 [QSA,L,E]
   RewriteRule ^([0-9]+)_([a-zA-Z0-9-]*)(.*)$ /prestashop1250/manufacturer.php?id_manufacturer=$1$3 [QSA,L,E]
   RewriteRule ^lang-([a-z]{2})/(.*)$ /prestashop1250/$2?isolang=$1 [QSA,L,E]
    
   # Catch 404 errors
   ErrorDocument 404 /prestashop1250/404.php

   You can generate this .htaccess file from admin panel at Tools tab, then choose Generators sub-tab, and follow the instructions carefully there. In this example above, I use prestashop1250 for the domain name. Please adjust it with yours.

2. Add this following code after the last line of that code above:

   # Remove Category ID from URL. You have to modify also the /classes/Link.php file! Modified by Masino Sinaga, May 3, 2010
   RewriteRule ^accessories-ipod$ /prestashop1250/category.php?id_category=3 [QSA,L,E]
   RewriteRule ^music-ipods$ /prestashop1250/category.php?id_category=2 [QSA,L,E]
   RewriteRule ^laptops$ /prestashop1250/category.php?id_category=1 [QSA,L,E]

   It meant that we will adjust the 3 categories name: accessories-ipod, music-ipods, and laptops. In other words, if you have more than 3 categories above, you have to define or add your own category one by one into the .htaccess file.

3. Open your /classes/Link.php file, and find this code:

   50 51 52 53 54 55 56 57 58 59

   public function getCategoryLink($id_category, $alias = NULL) { if (is_object($id_category)) return ($this->allow == 1) ? (_PS_BASE_URL_.__PS_BASE_URI__.intval($id_category->id).'-'.$id_category->link_rewrite) : (_PS_BASE_URL_.__PS_BASE_URI__.'category.php?id_category='.intval($id_category->id)); if ($alias) return ($this->allow == 1) ? (_PS_BASE_URL_.__PS_BASE_URI__.intval($id_category).'-'.$alias) : (_PS_BASE_URL_.__PS_BASE_URI__.'category.php?id_category='.intval($id_category)); return _PS_BASE_URL_.__PS_BASE_URI__.'category.php?id_category='.intval($id_category); }

   then replace with this following code:

   50 51 52 53 54 55 56 57 58 59

   public function getCategoryLink($id_category, $alias = NULL) { if (is_object($id_category)) return ($this->allow == 1) ? (_PS_BASE_URL_.__PS_BASE_URI__./*intval($id_category->id).'-'.*/$id_category->link_rewrite) : (_PS_BASE_URL_.__PS_BASE_URI__.'category.php?id_category='.intval($id_category->id)); if ($alias) return ($this->allow == 1) ? (_PS_BASE_URL_.__PS_BASE_URI__./*intval($id_category).'-'.*/$alias) : (_PS_BASE_URL_.__PS_BASE_URI__.'category.php?id_category='.intval($id_category)); return _PS_BASE_URL_.__PS_BASE_URI__.'category.php?id_category='.intval($id_category); }

Now you should have the URL without the category id. In the next article I will try to modify for the others (cms id, product id, etc).

When you activate Permalink feature from admin panel in Settings section for the very first time, then your WordPress will create an .htaccess file located on your web root directory (assuming this file does not already exist before). This .htaccess file contains of the code as you can see below:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /yourdomainnamehere/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /yourdomainnamehere/index.php [L]
</IfModule>

# END WordPress

Please note that yourdomainhere is the name of your domain.

When you deactivate this Permalink feature, then this .htaccess file would not be removed, but the main code above would be removed. It becomes like this:

# BEGIN WordPress

# END WordPress

This has been tested in WordPress version 2.8.4.