The MacOS package seems to be missing, but Windows package available on front page is essentially as good. All you need is WeiDU for MacOS, available
here. Place the files from the archive in your game directory; you know it's the right one if it contains a file called "chitin.key" and a directory called "lang" (assuming EE). From there it can be installed as any WeiDU mod [1]. The file "setup-d0questpack.exe" can safely be discarded.
1. The short version is: place weidu and weinstall on your path and make them executable, open a terminal in your game directory and use the command "weinstall d0questpack" without the quotes. Or rename a copy of weidu into setup-d0questpack, make it executable, place it in your game directory and run it.