Here is the full solution, thanks to michaelmior for his help, it got me half way.
  - Run this command to generate keys: - ssh-keygen
 - You'll get this output: - Generating public/private rsa key pair. Enter file in which to save the key (/home/user1/.ssh/id_rsa): Created directory ‘/home/user1/.ssh’. Enter passphrase (empty for no passphrase): (just hit enter, no need for a password) Enter same passphrase again: (same thing, hit enter again) Your identification has been saved in /home/user1/.ssh/id_rsa. Your public key has been saved in /home/user1/.ssh/id_rsa.pub. The key fingerprint is: xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx [email protected] 
 
- Add the public key to your - authorized_keysfile
 
- Move the - id_rsaand- id_rsa.pubto- /usr/local
 
- chownthe files to the same user as your webserver (in my case apache)
 
- chmodthe files to 600:- chmod 600 id_rsa*
 
This should now work.
 However, my installation kept hanging, a quick look at the httpd error_log file show me:
 PHP Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 2966269 bytes) in /var/www/sites/.... 
 Adding this code to the Wordpress wp-config.php file to temporally increase the amount of memory available:
 define('WP_MEMORY_LIMIT', '64M');