Download all dayz files from here http://www.mediafire.com/dayz
Make a new folder in your steam OA installasjon folder named @dayz. Inside @dayz folder make a folder named: addons . unpack all dayz files from mediafire link and copy them into @dayz>addons folder.
Start with Sixupdater and play. (make a new preset with the DayZ server of your choice)
NB! You have to manually update Dayz files. So check above link, everytime before you play or when the server tells you, for updated files.