Assuming you have migrated your products to LiteCart from another platform assigning the same IDs. Here are some good mod_rewrite rules for telling Google and others your pages have moved.

/.htaccess

  # Redirect old OpenCart URLs
  RewriteCond %{QUERY_STRING} route=product/category
  RewriteCond %{QUERY_STRING} path=([0-9]+_)?([0-9]+)
  RewriteRule ^index\.php$ /index.php/category?category_id=%2 [R=301,L]
 
  RewriteCond %{QUERY_STRING} route=product/manufacturer/info
  RewriteCond %{QUERY_STRING} manufacturer_id=([0-9]+)
  RewriteRule ^index\.php$ /index.php/manufacturer?manufacturer_id=%1 [R=301,L]
 
  RewriteCond %{QUERY_STRING} route=product/product
  RewriteCond %{QUERY_STRING} product_id=([0-9]+)
  RewriteRule ^index\.php$ /index.php/product?product_id=%1 [R=301,L]

/.htaccess

  # Redirect old osCommerce URLs
  RewriteCond %{REQUEST_URI} ^(/|/index.php) [NC]
  RewriteCond %{QUERY_STRING} cPath=([0-9]+)
  RewriteRule .* /index.php/category?category_id=%1 [R=301,L]
  RewriteRule ^.*-c-([0-9]+)\.html$ /index.php/category?category_id=$1 [R=301,L]
 
  RewriteCond %{REQUEST_URI} ^(/|/index.php) [NC]
  RewriteCond %{QUERY_STRING} manufacturers_id=([0-9]+)
  RewriteRule (.*) /index.php/manufacturer?manufacturer_id=%1 [R=301,L]
  RewriteRule ^.*-m-([0-9]+)\.html$ /index.php/manufacturer?manufacturer_id=$1 [R=301,L]
 
  RewriteCond %{REQUEST_URI} ^/product_info.php [NC]
  RewriteCond %{QUERY_STRING} products_id=([0-9]+)
  RewriteRule (.*) /index.php/product?product_id=%1 [R=301,L]
  RewriteRule ^.*-p-([0-9]+)\.html$ /index.php/product?product_id=$1 [R=301,L]

Be sure to add the rules before:

  # No logic for physical files
  RewriteCond %{REQUEST_FILENAME} -d [or]
  RewriteCond %{REQUEST_FILENAME} -f
  RewriteRule ^ - [L]

LiteCart can also resolve external URLs stated using the URL routing modules. Just append the result of the routes() method with more rules. Experimenting with URL parameters is not recommended.

includes/routes/url_category.inc.php

    function routes() {
      return array(
        array( // LiteCart
          'pattern' => '#^.*-c-([0-9]+)/?$#',
          'page' => 'category',
          'params' => 'category_id=$1',
        ),
        array( // osCommerce
          'pattern' => '#^.*-c-([0-9]+)\.html$#',
          'page' => 'category',
          'params' => 'category_id=$1',
        ),
      );
    }