compile:

./configure --with-irssi=~/src/irssi-0.8.15 make

install globally:

make install

install in home directory:

make user_install

load in irssi:

/LOAD icb /SERVER -icbnet icb default.icb.net

to make autoconnecting etc. work you'll need to edit config file and add to chatnets section:

icbnet = { type = "ICB"; };

then run once:

/SERVER ADD -auto -icbnet icbnet default.icb.net 7326

plus put into your ~/.irssi/startup:

load icb