Hi mate that's to difficult as demonel explain.
step 1: It's easier to copy your whole wow folder to another harddrive (externall or other partition).
-keep your original folder untouched, to play via skeleton in china
-rename the wow folder u just copy to wow-taiwan or whatever you like( this is only sugestion to easy remeber which cumtry you connect to, it's not mandatory to make it work)
-now change all the things in your copy wow back to original state, before you modify to play in china( remember do all of this in the wow folder you copied as mention in step 1!!
-start wow with original launcher put in any account name and pw, wow wil then patch itself to the latest version
-after you update your copy folder to the latest patch, change the realmlist as mention by demonel and your ready to play!!!
So easy no need to reinstall anything, when your done you should have 2 wow Copys on your pc one to play in china and one to play in USA or Europe or Taiwan( it just depends on the realmlist. WTF)
have fun and maybe you try to make a toon at the same server as demonel! I will also make a reroll later on.