Code:
on me:*:join:#:{
  updatenl
  var %i = 1
  while $nick($chan,%i,o) {
    .protect $nick(#,%i,o) $chan 2 $network
    inc %i
  }
}

If you don't want the protection to be channel specific, remove the $chan from protect line, also, if you don't want it to be network specific, remove the $network from that same line.