Pablo,

there was Milan Kosiva article in FoxPro Advisor May 1998
and sample fox code which uses info-zip dlls for packing and
unpacking.
My problem is that info-zip dlls will not produce
standard zip file structure. So I continue to
use RUN zip.exe / unzip.exe for packing.

Also info-zip doesnt support disk spanning. I'm thinking about
making a big zip file to c:\temp and then use fox code to span it
into disks.

Also, there is a possibility to use EasyZip (http://members.xoom.com/ipsoft/
), a free winzip clone which supports disk spanning and command line interface but this doesnt have separate dlls and is too big to be included
in distribution disks.