If you want to play in Chinese / Taiwanese version, you need to change the realmlist file from Asian servers ( e.g. cn1grunt.wowchina.com) to US servers (don't know the name). But in that case, you need to have the same game versions (TW and US). If it's not the case, you're gonna have to download or uninstall them.
If you want to play in English, then the easier would be to come with a USB key and the EN version inside and just launch your game normally (I won't mention latency problem ><).
Have fun!