This depends on Math::BaseCalc from CPAN. This is conveniently packaged in Debian as libmath-basecalc-perl. To fetch from CPAN if your OS doesn't provide CPAN packages, do $ perl -MCPAN -e 'install Math::BaseCalc' These perl modules assume they exist in a directory called Instance. The easiest way to make this fly, by far, is to symlink the place you got these sources as ~/.irssi/scripts/Instance. Then you can tell irssi to "/script load Instance/IrssiInstancer.pl" and everything should be fine. To run tests in the current directory, you should "ln -s . Instance" too. The UI is currently rather spartan, defining the following commands: /instance [label] sets the default instance for the current window to label, or stops sending default tags if label is omitted. /instsay label message sends the message with the given instance label but does not set or alter the default. /instpunt label Causes the current window to not display messages tagged with instance "label". /instunpunt label Undoes the action of the punt command. /instlist Lists punted (and routed) instances in the current window. /say message [Not defined by this script] will send the message to the current window without an instance label, even if a default is set. We suggest that you alias commands to more convenient forms: /alias i instance /alias il instlist /alias ip instpunt /alias is instsay /alias iu instunpunt See TODO for things if you want to help out.