As of now, q3py is only available as a source code download. As such you will need to install all the dependencies to build it.
wget https://github.com/robo9k/q3py/archive/master.zip unzip q3py-master.zip && cd q3py-master/
You need to download the source code of q3py. The easiest way is to grab the current master branch tarball (a zip actually) from GitHub. After downloading, extract the source code somewhere.
sudo apt-get install build-essential autotools-dev python3-dev
To compile q3py, you need a C99 compiler such as GCC (clang works as well). Furthermore you need the GNU autotools and the Python 3 header files and library.
autoreconf --install && ./configure && make
You then run the autotools to create a Makefile and such, configure q3py and finally run make to compile everything.
sudo make install
To install q3py after compilation, just run the install Make target as root, which will install q3py as a system package.
Install to local directory without root
Since q3py is meant to work with any Quake 3 fork, you now need to install it for your game.
ln -s /usr/local/lib64/q3py.so ~/.q3a/q3py/qagamex86_64.so
This creates a symbolic link from the q3py system package to a “q3py” game directory for the Quake 3 installation of the current user.
You need to configure Quake 3 to use the game directory in which you just installed q3py (unless you use the BASEGAME, e.g. “baseq3”).