For CentOS 6.0, during installation you can select the Language option and Chinese Support. The language will be available for you to use. Go to 'System'->Preferences-> Input Meth... [by sumoo2011]
I have just installed Lubuntu 14.04.1 LTS (Trusty Tahr) and I need to input Chinese traditional and simplified characters. I have successfully installed Language Support. But in "Keyboard Input Methods" no Chinese options are there of any kind.