## Install prerequisites to build Varnish and configure system path
sudo port install automake libtool pkgconfig pcre
export PATH="/opt/local/bin:/opt/local/sbin:$PATH"

## Make sure ~/src exists and then downloads and extracts Varnish there (change as required)
mkdir -p ~/src && cd ~/src
wget "http://downloads.sourceforge.net/project/varnish/varnish/2.1.3/varnish-2.1.3.tar.gz"
tar xvzf varnish-2.1.3.tar.gz && cd varnish-2.1.3

## Build Varnish with it's install location as /opt/local/ (change as required)
## For example, varnishd will be installed to /opt/local/sbin/ for neatness
./autogen.sh 
./configure --prefix=/opt/local && make
sudo make install