I cannot access to the console from the UI. I just want to setup my wifi card from console. I've tried with Shutdown or reboot and esc without success. I haven't an ethernet router port.
Is there anything more?
With Raspbmc, exit XBMC from the shutdown menu (choose exit, not shutdown). At the blue screen press Esc and you will be greeted with a login prompt. The default username is "pi", the default password is "raspberry". I believe you can also press Esc during boot to access the console. Alternatively you could log in via SSH.
This will not work on OpenELEC.