The easiest way to do it is that modify the mt.cfg file under cgi-bin folder. There are two things need to be set up:
1. set NoHTMLEntities to 1
2. set PublishCharset to UTF-8
The reason set the publish character set to UTF-8 instead of GB2312 is that you can enable both Simplify Chinese and Traditional Chinese. Also, even Japanese and Korean can be accepted by the system.