Just untar it over the directory. Despite tar's archaic options, I prefer doing this from a command line, so something like this should do the trick:
Code:
su -
tar -zxvf /path/to/patch/dompatch212_linux_x86.tgz /usr/local/games/dominions2
Sorry about the star (No, it wasn't me, honost!)
__________________
"It makes you wonder if there is anything to astrology after all. "Oh, there is," said Susan, "Delusion, wishful thinking and gullibility." (T. Pratchett)