You cannot write characters with accents on Linux console while in Unicode mode?
The dead keys functionality for Unicode mode needs some more love.
A workaround is to convert the console keymaps so that they do not require dead keys. For example, with dead keys, to put an accent on "a", you would normally type ";", then "a". You can convert the keymap so that, e.g. Alt+a will print the "a" with an accent.
To sum up on current support on Linux Console (that's not xterm but what you get with Ctrl-Alt-F1 :), you can view documents in Unicode from a wide range of character sets as long as combining characters are not required (Hindi no, Vietnamese yes). You can input (write) in Unicode mode as long as no dead keys are involved.
A dead key is a key that when you press it nothing happens. You press a second key and the character prints (for example, ";"+"a" for ά).