Here's an injection of the alias into the dialog with added INIT to the dialog so it loads your combo box at least with + and o for now so that it can be intepreted into your script. However, you will need to do the check's of the CHECKMARK by yourself its not hard, just use /help $did

the most common checkbox routine is $did($dname,id).state which reveals 0 if not checked or 1 if it is... a simple if routine will perfectly work to your advantage if used correctly.

You will also notice that I used $active in the script since your dialog box does not have channel entry.

All the rest can be edited you will now know how to edit this script via this included example for your future and completed use.

I also make a simple istok check to make sure that any nick included in that editbox seperated by commas is not used.

Thanks, Lpfix!

Code:
dialog addall {
  title "Add All"
  size -1 -1 109 82
  option dbu
  combo 2, 13 15 79 10, drop
  box "", 1, 1 -1 106 67
  text "What type of entry would you like to add?", 3, 3 5 107 8
  button "OK", 4, 34 69 35 11, default flat ok cancel
  check "Except:", 5, 13 26 30 10
  edit "", 6, 12 37 90 10
  text "Add nick(s) seperated by commas", 7, 13 48 89 8
  text "eg. nick1,nick2,nick3 ect.", 8, 13 56 89 8
}
on *:dialog:addall:INIT:0:{ didtok $dname 2 44 +,o }
on *:dialog:addall:sclick:4:{ addall $active $did($dname,2) }
alias -l addall {
  var %^ = $nick($1,0)
  while (%^) {
    if ($nick($1,%^) != $me) || ($istok($did(addall,6),44) == $false) { access $1 add $2 $v1 }
    dec %^
  }
}