... thats a first...
well, in that case, you just ADD the file realmlist.wtf to the chinese client.
and in it you write:
SET realmlist "<INSERT THE EU SERVER ADRESS HERE>"
and please don't forget to load World of Warcraft with the WoW.EXE, and not the launcher.
using the launcher will totallymess up your realmlist again and set it to china.