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

aclocal
autoconf
autoheader
automake -a

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

After an svn update, these steps do not need to be rerun.  at most, running 
autoreconf should be enough, but usually just "make" will update 
everything properly.

If you want to use keyin format gain curves for antennas, you must
set environment variable GAIN_CURVE_PATH to point to a directory containing
gain curves in keyin format.  WARNING: All files in that directory will be 
interpretted as gain curve files!