Locale problem on my desktop

After 3 days of emerging, finally I have GNOME 2.10 with some useful programs installed, but I found that SCIM 1.3.1 seems dropped the support of non-UTF-8 locales like zh_HK.Big5-HKSCS or zh_TW.Big5, this is quite confusing in the beginning, but now, after some trials, I modified my system locale to zh_HK.UTF-8 and I can view and type chinese correctly.