Right now to enter Korean, Japanese, Chinese and other languages which depend on a IME you need to use the "Character Input" dialog. This can be accessed when you click the "Char Input" button which is shown when you start editing the text of an element.
Just came about this entry. Works fine for headings or paragraphs, but how can you add special characters to other elements e.g. form select? There you're not using the regular text editor and so char input is not available (or I can't find it).