"You all are reading our newspaper."
Translation:Ihr lest unsere Zeitung.
Na ja . . . "you all" is indeed a bit slangy. Not as much as "y'all", but I would disagree that it can't be translated directly. In fact, I find it helps overcome the lack of a dedicated second-person plural pronoun in English. (To be very specific, you're right, dpchalmers, that the "all" alone isn't directly translated: I am considering the paired words.)
Most people would probably find it more grammatically acceptable to reorder the words and say, "You are all reading . . . . ," thus incorporating the collective/plural aspect whilst avoiding the very colloquial "y'all".