Offering chats and sending files with DCC is only supported in Emacs 22.  Accepting chats and receiving files should work in all versions.

-- Can anyone say whether or not it works in [[XEmacs]]?

Otherwise, getting DCC (Direct Client-to-Client) to work in erc is trivial. Just add ##(require 'erc-dcc)## in your ##~/.emacs## file. You can load it directly too, without editing the ##~/.emacs## file, just to test it. Just ##M-x load-file RET erc-dcc.el##. There is not much documentation around on erc-dcc so the source would be your best doc.

Usage:

Accept a pending DCC chat offer from nick or offer DCC chat to nick:

    /dcc chat nick

If a user offers you a file via DCC: 

    /dcc get nick

To send a file via DCC:

    /dcc send nick file

or ##M-x erc-dcc-send-file RET <nick> RET <file>##

To list all DCC offers and/or connections:

    /dcc list

To close a DCC connection type the following (where type can be send, get, or chat - both type and nick are optional):

    /dcc close type nick

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[[ERC]]