Doesn't the function refreshScreen in reply 14 do exactly what is required?
Of course, the somewhat wasteful array "pixels" (1024 bits of RAM to store 64 bits of data! :o ) has to be filled with the correct data first, but that's what setupChar does, albeit for an arbitrary string, though this would be simple to change to a single function parameter.
I too fail to see how this code is irrelevant.