The following article : Step by step introduction to switching your debian installation to utf-8 encoding.
may be of help.
How to make irssi talk UTF8 on a classic ISO-8859-2 terminal, flash HOWTO:
* You need irssi sources.
* make, make install
* In irssi: /load charconv (Ignore the configuration file error.)
* /set term_type 8bit
* /set charconv_terminal_charset iso-8859-2
* /set charconv_fallback iso-8859-2 (Some unfortunates still use this, so do this to be able to still read them.)
All the characters in this HOWTO are Unicode and there was no glyph harmed while making this HOWTO.