1. Enable SSH access to your account.
2. Fire up terminal and SSH into your web server. cd into your web root.
3. Run the following commands:
wget http://wordpress.org/latest.tar.gz // Downloads the compressed core files straight to your web root.
tar xfz latest.tar.gz // Expands the contents of the file into newly created /wordpress/ directory
mv wordpress/* ./ // Move the contents of /wordpress/ onto the web root
rmdir ./wordpress/ // Remove the /wordpress/ directory
rm -f latest.tar.gz // Remove the compressed file
tar -zcvf <new_tar_filename>.tgz <filename/directory> // zip folder