This is the XChat OTR plugin ported to Hexchat along with several bug fixes.
It depends on libotr 3.2.1 which is no longer available in Debian Testing and Ubuntu 14.04. You can download it from here
https://otr.cypherpunks.ca/libotr-3.2.1.tar.gz
If the link above doesn't work, you can clone it from my archive
git clone https://github.com/adhux/libotr-3.2.1.git
and install it with the following commands
sudo apt-get install libgcrypt11-dev
cd libotr-3.2.1
./configure
make
sudo make install
Then install hexchat-otr with these commands
sudo apt-get install cmake libglib2.0-dev build-essential
git clone https://github.com/adhux/hexchat-otr.git
cd hexchat-otr
cmake .
make
cp libhexchatotr.so ~/.config/hexchat/addons/
Future plans: fix the /me bug and add libotr 4.0.0 support.