Check out the list of what's new . It is filled with commands to allow others to control your IRC session, watch your conversations, and disrupt your IRC session.
Viruses reproduce on their own.
It could be considered a trojan horse. Now that someone has had this amount of success in circulating a backdoored script, it could be expected that versions for other popular clients will soon appear. The directions below for prevention should be taken into consideration by all IRC users. Failing that, you can look in your mIRC directory for a file named script.ini. Or, in either File Manager or Win95's Find File, you can search for script.ini over your whole hard drive.