Im not sure about the civ2 style batte sounds
but you can replace all the sounds if you want...
you just have to make a .wav or mp3 that matches the format of the original sounds... (and close to the original sound duration

)
I did it for alot of sounds (air bombing/declare war/cheer/battle victory/etc) and they worked fine!
as for the civ2 as long as they are in a format that can be converted to .wav or mp3 I dont think it should be a problem