The text editor vim supports Big5 encoding. You will also need to set vim to use a font that includes the set of characters needed.
Vim commands for encodings include
:e ++enc=big5 (reload current file using big5 encoding)
Notepad++ v5.6 new features and fixed bugs (from v5.5.1)
Add languages encoding - Chinese traditional (BIG5), Chinese Simplified (GB2312), Japanese (Shift JIS), Korean (EUC), Thai (TIS-620), Hebrew (iso-8859-8), Hebrew (1255), Central European (1250), Cyrillic (1251), Cyrillic (KOI8-U), Cyrillic (KOI8-R), Cyrillic (Mac), Western European(1252), Greek (1253), Turkish(1254), Arabic (1256), Baltic (1257), Vietnamese (1258), ISO_8859-1 to ISO_8859-16 and a lot of more.