Nothing is encoded. They are standard ZIP files. When unzipped, they give you the useable files. Everything will be quite useable in CC3.
If you want to use them in CC3, I'd suggest that you download the Dundjinni (TM) version. The graphics there are best suited for CC3 conversions.
However, I haven't used CC3 for a good year and a half, so I don't remember anymore what you have to run in CC3 to convert them into files with the proper CC3 scaling. On the CC3 mailing list in May or June 2008, I believe, Ralf Schemmenn of ProFantasy posted a message telling how to do that. You could search the CC3 mailing list archives for that information, or you simply could E-Mail Ralf and ask him. He's available at:
ralf@profantasy.com
He's also a member here under the user name Uthoroc.
http://www.vintyri.com
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Mark Oliva
The Vintyri (TM) Project