This plugin comes packaged with LuaJ. LuaJ is a Lua interpreter based on the 5.2.x version of Lua. See http://www.luaj.org/luaj/3.0/README.html.
If the Console plugin is installed, this plugin automatically sets the system environment variable LUAJ to the path of luaj. So to run a script called 'script.lua', cd to the file's directory (cd $d) and run:
java -cp "$LUAJ" lua script.lua
LuaJPlugin.jar is necessary for the plugins LuaJShell and LuaJShellSE (LuaJ shell for scripting engine).