ircII help: window server

Usage: SERVER <server>:<portnumber>:<password>:<nickname>
  This allows you to specify a different server to connect to for 
  the current window. The <portnumber> and <password> are optional. 
  If you are already connected to the specified server, the window 
  will switch to that server.  Doing a WINDOW with no parameters 
  shows you what server is associated with it.

See Also:
  HELP SERVER