ircII help: sendline

Usage: SENDLINE <line of text>
  SENDLINE will send a line to the client EXACTLY as though you had
  typed it at the command line.  However, unlike TYPE it is not
  displayed in the command line.  All alias expansion or command
  processing is done after it's sent as it normally would be when you 
  send a line with RETURN.  It can be used with ON ^INPUT
  if you're extremely careful.

See Also:
  ON INPUT
  SET INPUT_PROTECTION