Re: Alchohol 120%
^^ that would probably depend on the country.
Bypassing copy protection is illegal in some places, in some places you can do it if it's for your own use.
Anyway, alcohol 120% might be able to do it, worth a try. I have tried it only once and wasn't able to get past the copy protection, but some people say that alcohol 120% works.
And if it doesn't you could always just download the expansion as a torrent, and use the cd key that you have.