how to modify fonts competely??

[jilingshu]

hi,all
now i want to modify the eq2's fonts,not only the chat fonts but also the system fonts like login screen and so on.
i try to translate eq2's ui into chinese and i find that the default fonts cannot show chinese characters.so i want to use 'Hei' to instead the default fonts.what files should i modify?i try to modify the eq2_fonts.xml and eq2_textstyle.xml,but it takes no effects.
could u give me some advices?
thx!