This is how I got InfluxDB (last stable - 0.8.8) working on FreeBSD 9.3-RELEASE-p9
First make sure sed resolves to gsed, than you don't have to patch that many files .. I solved it this way:
mkdir ~/bin
ln -sf /usr/local/bin/gsed ~/bin/sed
export PATH=~/bin:$PATH
Install required pkgs, setup env and download source.