Get TRAMP (Transparent Remote file Access, Multiple Protocol) :

http://savannah.gnu.org/projects/tramp/

Install it :

cd ~/.emacs.d/
tar -xvzf /your/download/folder/tramp-2.X.X.tar.gz
ln -s tramp-2.X.X tramp
cd tramp
./configure --with-contrib
make
sudo make install

Configure your emacs to use it :
1. Add the following in your .emacs

;; Remote file editing via ssh
(add-to-list 'load-path "~/.emacs.d/tramp/lisp/")
(require 'tramp)
(setq tramp-default-method "ssh")

2. Launch your emacs
3. C-x C-f /[email protected]:/path/to/file

Warning :
Seems it doesn't work if no password is required to login to host (using public key for example). But not sure at all...