irc's clients should have dcc ....thas the best way to chat/download. downloading through the irc servers are a bit irritating and it purely relies on your internet connection. and some irc servers have a limited bandwidth allocated to its users
you cant download at more than that speed. moreover downloading through the irc depends on the connection on that particular server. netsplits are the most devastating thing that can occur on irc's (in some cases frequently) .....its advised to switch to a server on which the user from whom you r downloadg the file is on.
there r fserve scripts for channels which provides download contents ...which they themselves give away freely or if you check their site they mightve adviced their users to download a particular script which is attuned to work on that particular channel.