The LuaPOD module is included in the subversion repository (in "dependencies") and will be installed automatically. In order to use it, however, you will need also to have the Lua LPeg library installed in your Sputnik directory. To do this, you will need to download and and compile the LPeg library and then move the lpeg.so file that will be created to your Sputnik installation.
The compilation can be done in any directory:
cd /tmp/
wget http://www.inf.puc-rio.br/~roberto/lpeg-0.6.tar.gz
tar -xzvf lpeg-0.6.tar.gz
cd lpeg-0.6
make
The compilation will create a file called lpeg.so. Move it to the lib/lua/5.1 directory in your Sputnik installation. E.g., if you installed Sputnik in '/home/joe/sputnik' you will need to move lpeg.so to /home/joe/sputnik/lib/lua/5.1/:
cp lpeg.so /home/joe/sputnik/lib/lua/5.1/
Now everything should work and you can use LuaPOD.
For more information about LuaPOD see LuaPOD documentation.