What do you mean by activating? The language for iPlotz online application can be changed by selecting a language from the drop-down located at the top in the login box in the url http://iplotz.com/app .
Now i have just noticed the drop-down menu in the login box, but i use the desktop version. Can i change the language of the desktop version?
I don't really need an Italian version of Iplotz, because I'm ok with the english version too, but if there was a version in my language i would be glad to use it :-)