It isn't terribly hard to write the bridge code to lua, just monotonous to translate inputs and outputs from C++.
You throw a lua function into a table (usually tables are used as namespaces and globals are just a table) and then make that C++ translate to your normal one and handle the return value correctly.
The hard thing is building a system to pass in a C++ object in general as that required building a table for each instance that matches its class.
