(1) Install the ffcall library, if you do not already have it installed.

If it is already installed, you will have, for example, an "avcall"
library, man page, and avcall.h header.  You can skip to step 2, and
if ffcall is not installed, you will be given an obvious error message.

ffcall is available from http://directory.fsf.org/wiki/Libffcall
and various other places.  Several platforms have their own distributions.

    debian: apt-get install libffcall1 libffcall1-dev
    redhat: http://rpmfind.net/linux/rpm2html/search.php?query=ffcall

    [please contribute more distros]

(2) Now, build the FFI package in the usual manner.

   perl Makefile.PL
   make
   make test
   make install

See the pod documentation for details of usage.