There are around 7 base wpi packages and 7 language wpi packages; DE, US, ES, FR, IT, NL and RU. To access the download page, one must have bought a support unit in the past or present. Once done, a password will be emailed to you if you have bought a support unit. If purchased for a prior version, one will be emailed a new password to download with a request to please purchase a new support unit. I have it installed on AraOS 5.03.
There is also an RPM wpi. Not sure what this one does.