Transparent decompression (-z option) is available on Linux kernels
using kernel version 2.4.14 or 2.4.9-ac14 or later.

You also need the zisofs-tools package, containing the mkzftree
utility, to create the compressed files; this package is available at:

ftp://ftp.kernel.org/pub/linux/utils/fs/zisofs/

The mkzftree utility can also be used to read compressed CD-ROMs on
systems which do not support transparent decompression.

The use of a separate utility allows compression to be controlled on a
per-file basis.  A file which is not compressed can be read on any
system.

Transparent decompression is implemented as an extension to Rock
Ridge, so Rock Ridge needs to be enabled (-R or -r options.)