Good news for Linux/UNIX users:
Fellow scambuster Mike Frysinger has created a C program which extracts the contents of ZIX archives, and put the package online. He calls it funzix, and its homepage is located at http://funzix.sourceforge.net/
It's a command-line utility, and has been confirmed by Mike to work with both version 1.0 and 2.0 zix archives.
The package can be found at SourceForge, and is supposedly platform independent. Since his development platform is unix-based, developers working in other platforms may have to do some massageing to build. In particular, the makefile. What needs to be done should be obvious. Also, you'll need a copy of the ZLIB library, if you don't already have it installed.
Since I posted this entry, I've had the chance to check out his code. It's pretty good; nice, clean and well-commented.
If I have one hesitation, it is the choice of the stdio file handling functions. Invented in a time out of mind, I'm not sure they stand up to the 4GB barrier.(some internal file pointers need to be quad-words, a need unconceived of when the FILE structure was invented). This may have been patched in recent versions and builds of common C development kits and libraries, but you should check your development environment for this.
Kudos to Mike for getting involved, and for sharing his efforts with the rest of us.