Not really true, not only is there not a "Public" one, there is absolutely nothing I could find talking about a "private" one either. Not a name of a program, not any commercial "BUY A WAD PACKER" or "CREATE WAD FILES". I even spent a few hours in the homebrew "scene" if you will, i'm sure as hell I could create a homebrew game all by myself, create elf files and the whole thing, but I still have no clue how to create WAD files from .app files.
Anyways long story short, there is no method for us mere mortals to pack these files (if they are even real) into something use'able. It may have been released this way as proof-of-concept to ensure that the masses do not have access to Virtual Console exploitation.