Italian listings are provided by the tv_grab_it script which uses data from variuos web sites.
Due to major changes in the layout of those web sites, starting from february 2009 you need at least xmltv version 0.5.55. If your distro comes with an older version, you'll have to manually install the new one. See XMLTVSource.
Once installed, to configure xmltv you must run
The script will download the list of available channels and ask you to choose which one you want to grab. It will than save a configuration file in ~/.xmltv/tv_grab_it.conf
Recommended usage, as of tv_grab_it author's advice, is:
tv_grab_it --cache --slow --cache-slow --errors-in-xml
With the above command, tv_grab_it will download 7 days of full data, including programs descriptions and additional data like director and actors for movie events (when available).
Please keep in mind that this is a very slow process (it keeps about 2 hours for 15 channels), so you better set up a nightly job using cron to fetch the listings. Refer to XMLTVGrab for more info on this topic.