I have seen that script maked by another user on that web but the code was really not good so I have decided to correct it with nearest 10 lines less than the first :D

well, press ctrl on your keyboard and with your mouse select all the nicks wichs you wish to change there chanmode voice op devoice deop...
and type one of this
note: you can select a large number of nicks without get self flood, but I haven't maked this script for the lamers

/changemode +v
/changemode -v
/changemode +o
/changemode -o

alias changemode {
  var %t = $iif($modespl < 6,1,0.5), %i = 1
  if ($snick($active,0) == 0) {
    echo -at $me $+ , there's no selected nickname in the nicklist. blind ? :p
  }
  else {
    echo -at going for give $1 at $snick($chan,0) $iif($snick($chan,0) > 1,users,user)
    while (%i <= $snick($chan,0)) {
      var %snicks = $addtok(%snicks,$snick($chan,%i),32)
      inc %i
      if ($numtok(%snicks,32) == $modespl) {
        .timer 1 $calc(%t * %i) raw -q MODE $chan $+($left($1,1),$str($mid($1,2),$modespl)) $sorttok(%snicks,32)  
        %snicks = ""
      }
    }
    if (%snicks) { raw -q MODE $chan $+($left($1,1),$str($mid($1,2),$modespl)) $sorttok(%snicks,32) }
  }
}