Hello,
[...] help me to implement some new features!
Depending on the features you want to implement, and the degree of maturity you require, metalua might interest you:
http://metalua.luaforge.net
For syntactic features, it's sometimes an overkill (and purely syntactic extensions are often a bad idea to start with); for semantic extensions, it's quite right; it won't help you if you plan to hack the VM, though.
