#get latest package and check md5sum

wget http://wordpress.org/wordpress-2.9.2.tar.gz
md5sum wordpress-2.9.2.tar.gz
lynx -dump http://wordpress.org/wordpress-2.9.2.md5

#if md5sum is OK (should be 6023fe6701476c8152bda5d4c6277c69 ), then continue 

tar -zxf wordpress-2.9.2.tar.gz
cd wordpress
cp wp-comments-post.php /replace_your_wordpress_directory_here/wp-comments-post.php
cp wp-includes/version.php /replace_your_wordpress_directory_here/wp-includes/version.php
cp wp-includes/functions.php /replace_your_wordpress_directory_here/wp-includes/functions.php
cp wp-includes/query.php /replace_your_wordpress_directory_here/wp-includes/query.php
cp wp-includes/http.php /replace_your_wordpress_directory_here/wp-includes/http.php
cp readme.html /replace_your_wordpress_directory_here/readme.html
cp wp-admin/includes/plugin.php /replace_your_wordpress_directory_here/wp-admin/includes/plugin.php
cp wp-admin/includes/update-core.php /replace_your_wordpress_directory_here/wp-admin/includes/update-core.php
cp wp-admin/menu.php /replace_your_wordpress_directory_here/wp-admin/menu.php
cp wp-admin/edit-category-form.php /replace_your_wordpress_directory_here/wp-admin/edit-category-form.php
cd ..