What previous post? - - there isn't one, not on this thread.
Looks like Benq have withdrawn scanner support on their websites, I don't think they make them any more, otherwise they would have been the best source for drivers. However, if it's an old scanner, it's unlikely there will be any Windows 8 drivers for it anyway, wherever you look or search.
This is probably your only option (short of buying a new scanner):http://www.hamrick.com/vuescan/acer_benq_5160c.html