I'm having this exact same problem and trying to do the same thing (get an AZW4 readable on my iPad).
I've got mobiunpack 31 (is that the right one to use?) but I don't know what to do with it. I tried following the instructions in this thread: (
https://www.mobileread.com/forums/sho...d.php?t=121815)
But I just got DOS error messages saying invalid command lines.