Tiberian Sun English Voice Audio Pack addon

how is that an addon?

Why would anyone want that? :-\

btw, you don't need the 1.06 mod system for this at all. Just rename it to sc*.mix format (e.g. sc-tse.mix) and it works. Any sc*.mix file is accepted by the game as addon. The only limitation to this is that unpatched 1.04 cannot use it to override files inside update.mix and updatec.mix.

Well, there's one more limitation; even in the 1.06 patch you cannot override the contents of cclocal.mix. But the modding system ini settings in 1.06 are designed to get around that by giving alternate names for the files that are read from it (mostly just the mouse cursor and font files).