Only scripts (mIRC program) Work for IRC servers. Bots are programs made for a particular chatnetwork such as AOL and Yahoo and others.
Although bots made for those chats are pretty much created just to annoying other chatter with porno spaming, and other advertising while they are in the room.
Scripts (mIRC programs) are a good tool for hosting a room since they can manipulate the server with others commands that aren't include on the regular web chat.
People whom made bots for MSN chat always include these commands in their creation providing the tools that come in mIRC so they also can manipulate the server at MSN chat. However the conection files in bots for MSN are good only for MSN.
Some of popular bot for MSN are. ViperBot, IRCDominator, Shadow FX, and others.
Some of popular Script for MSN are. Hybrid Omega, Kenobi script, Guarddog Script, and others.
If you like to try and make your own script I would suggest you to get a plain version of mIRC and a connection file, Vincula is the most popular maybe.
If you like to try and make your own bot start learning some programing maybe and keep playing around.
Or if you like just get one of those already made the most that you like and have fun with it.