There has to be a better way, but this is all I can think of at the moment:
Code:
alias checkchan {
  var %n = $scon(0)
  while (%n) {
    if ($scon(%n).network == %network1) {
      var %i = 1, %c = #chan1 #chan2 #chan3
      while ($gettok(%c,%i,32)) { var %v1 = $v1
        echo -a I'm $iif($me ison %v1,ON $v2,NOT on $v2) 
        inc %i
      }
    }
    elseif ($scon(%n).network == %network2) {
      var %i = 1, %c = #chan4 #chan5 #chan6
      while ($gettok(%c,%i,32)) { var %v1 = $v1
        echo -a I'm $iif($me ison %v1,ON $v2,NOT on $v2) 
        inc %i
      }
    }
    dec %n
  }
}
And basically you do the same thing by adding another elseif statement for another network with their own channels...so on and forth.