Hello,
For anyone interested, I have uploaded UniLua to github (
https://github.com/xebecnan/UniLua),
which is a pure C# implementation of Lua 5.2 focus on compatibility with Unity3D. And it's used in a developing commercial MMORPG game.
Instead of translating Lua bytecodes into MSIL running directly on .NET VM, it runs a Lua VM on .NET VM. So Lua code could be loaded at runtime, and it maybe an advantage over other script languages for Unity3D.
Wish it could help people who want to use Lua in Unity3D :)