Sure, you can do a relay, but that's kind of annoying in the end...

Code:
on *:text:*:#: {
  if ( $chan == #chan1 ) {
    if ( $server == some.irc.server
      scon !msg #chan2 $+([,$nick,]) $1-
    }
  }
  if ( $chan == #chan2 ) {
    if ( $server == some.other.irc.server ) {
      scon !msg #chan1 $+([,$nick,]) $1-
    }
  }
}


Pretty sure that'll work.