There's actually an OS X port, done in 2004 by one of the programmers. It was on his iDisk, and went unnoticed by many people. I forgot the who/why etc, I'd love to get more info.
Port still works under the latest Mac OS on Intel machines, everything except music and some graphical issues (no live updating of attacks, only at the end)
Civ II is my favorite as well! There's also an OS X port of Sid Meier's Alpha Centauri as well.
Pro-tip for Civ II under OS X - Make sure to set auto-save on each turn, cause it will crash every few hours.
http://www.megaupload.com/?d=DCHVZZ6Z - The OS X app, just place in your folder with a full install of Civ II.