difxio installs in a way that should be familiar to most that have installed
modern Gnu software.

To install from a .tar.gz distribution:

tar zxvf difxio-XXX.tar.gz
cd difxio-XXX
./configure --prefix=${DIFXROOT}
make
(maybe become root here)
make install


To install from a fresh svn checkout, run the following:

aclocal
libtoolize --copy --force
autoconf
autoheader
automake -a -c

./configure --prefix=${DIFXROOT}
make
# (su root?)
make install

After an svn update, these steps do not need to be rerun.  usually just 
"make" will update everything properly, but sometimes it is necessary
to run "autoreconf" before compiling again.  If that doesn't work,
one can always fall back on the above sequence of commands.

A make install will copy libraries into <prefix>/lib .  Make sure this
path is either in /etc/ld.so.conf (ie, for /usr/local and /usr, usually),
or in your LD_LIBRARY_PATH.  In the former case, running /sbin/ldconfig
might be necessary to update some files.

make install will also copy a package config file into 
<prefix>/lib/pkgconfig.  Make sure this path is in your PKG_CONFIG_PATH
if you are to compile against this library.  you can test this by
running

pkg-config --cflags difxio

If you get a sensible answer then you are set.