gzip -dc gcl-2.2.1-beta1.tgz | tar xvf -
cd gcl-2.2.1
[ if the tclConfig.sh and tkConfig.sh are in /usr/lib on slackware add
 a third argument to ./add-defs to give that directory... ]
% ./add-defs 386-linux /usr/lib
% make
% make install "PREFIX_DIR=/usr"