The asnswer is for the @enberg guy from https://gist.github.com/enberg/84710b619bdb0b10e945. He made a script to install it.
#!/bin/bash
WORKDIR=`mktemp -d` && cd $WORKDIR
# Get deps
sudo apt-get -q update
sudo apt-get -qy install make libfuse-dev g++
# Get, make and install unrar
wget http://www.rarlab.com/rar/unrarsrc-5.1.1.tar.gz
tar zxvf unrarsrc-5.1.1.tar.gz
cd unrar
make && sudo make install
make lib && sudo make install-lib
cd ..
# Get, make and install rar2fs
wget https://googledrive.com/host/0B-2uEqYiZg3zR1F0b0tmRktiaXc -O rar2fs-1.20.0.tar.gz
tar zxvf rar2fs-1.20.0.tar.gz
cd rar2fs-1.20.0
./configure --with-unrar=../unrar --with-unrar-lib=/usr/lib/
make && sudo make install
# Cleanup
rm -rf $WORKDIR
give an execute permission
chmod +x install_rar2fs_ubuntu.sh
Then run the script from your terminal
sudo ./install_rar2fs_ubuntu.sh