Basically, if the whois infomation is not displayed well, that would mean your are using non UTF-8 encoding. what you need to do is to convert the encoding to your current settings, Here's a command line example:

$ whois 6k.cn

You might see some malformed chars, let's convert them directly:
$ whois 6k.cn | iconv -f utf8 -t gbk
Now, It's Ok, and you can see the Chinese characters.