Download the tclwebtest source, unpack it, and put it an appropriate place. As root:

cd /tmp
tar xvzf tclwebtest-0.3.tar.gz
mv tclwebtest-0.3 /usr/local/
ln -s /usr/local/tclwebtest-0.3 /usr/local/tclwebtest
ln -s /usr/local/tclwebtest/tclwebtest /usr/local/bin