Adding functions to libcod made by others

[Ni3ls]

Hi all,

Mitch made some nice extra weapon function and so did filthy. Filthy explained how to add it to my own version in libcod in his thread, but I dont understand it. How to add other people findings to your own libcod version?

EDIT:
Editing the files I understand, but the compiling part is driving me crazy. How to compile on Linux? I searched on google, but it's still unclear