ORIGINAL: hobbes
It might be a bit unethical but I would have thought any game could simply look at a
particular folder and play everything there in alphabetical order. Then one could simply
copy all the sound files from EUII or any other game into that folder.
Perhaps if you copied the EUII music folder onto your desktop, then renamed the music files exactly as they are in CoG, coverting them to .wma files in the process, then replace the existing CoG music folder with this one, it might work...I think there are more music files in EUII though, so you would have to create additional Msc and Sad files....of course save a copy of the original CoG music folder in case it does not work...if I can find my copy of EUII, I'll give it a go myself...
...and as far as it being ethical, I own both games and would do this for my own personal enjoyment while playing the game, so I see it as no problem...