If you have darwin ports installed on OS X then you can follow the instructions below. If you don't want to go thorough the trouble of installing darwin ports just so you can use wget then you can just hop on over to the lua downloads and drop the tar file into the /tmp dir and follow the rest of the instructions

Open up terminal. Copy the link of the latest Lua version and download it:

cd /tmp
wget http://www.lua.org/ftp/lua-5.1.4.tar.gz

Extract and compile:

tar -xzvf lua-5.1.4.tar.gz
cd lua-5.1.4
make macosx

Test and install (if test goes through)

make test
sudo make install

And you’re done!