Hi Gianroberto,
You have to download the 4.2.2 eclipse version from this link: http://www.eclipse.org/downloads/download.php?file=/technology/epp/downloads/release/juno/SR2/eclipse-jee-juno-SR2-win32-x86_64.zip&mirror_id=575
You can follow the steps in this page: http://www.webratio.com/portal/content/en/download-ifml-editor and you have to create a new project in eclipse and select File -> New -> Other and select IFML -> IFML Model, if you can't see the palette, you have to go to Window -> Show view -> Other -> General -> Palette