(※Hanja: Kanji used in Korean)
First, in notepad
Input a hangul and press [ctrl] to convert to a hanja, and again input a hangul and press [ctrl] to convert to a kanji, and...
Somehow, you can convert hangul to kanji one-by-one
Which means, it's too slow and boring to input long Kanji-Hangul Mixtured article...
How to input Korean Kanji easier...
(1) Buy a word processor made in Korean (It's called 'Hangul 97', Right?) to use it.
Or use 'MS-Word'
Those word processors have the word-to-word hangul-kanji coversion option.
(2) Also Wordpad in Windows Vista has the hangul-kanji word-to-word conversion option.(But Korean IME 2007 must be installed.)
(3) If you can speak Japanese, and if you don't have any of them(Hangul 97, MS WORD, wordpad in VISTA)....
First, input kanji vocabulary by using Japanese IME
And, input hangul between Kanji vocabularies.
(Of course, perhaps there can be some differences between Sino-Japaneses and Sino-Korean. But absolutely most of (maybe 95%?) of Modern Sino-Korean vocabularies (not Classic Korean) are from 'Modern' Sino-Japanese vocabularies. (well, it's the matter of the pronouncations, though.) )