Some IRC clients such as ircII, Epic, BitchX and so on may not come with a full european setting to be able to display characters such as å, ä, ö, ü, µ, € and so on properly. This is the way to fix this.

First set your language environment to avoid unicode:

export LANG en_US

Then start your IRC application and enter the following commands:

/set eight_bit_char on
/set translation Latin_1

Now you should be able to use it properly.