Apparently the javascript I used fails to work in IE, so that may explain some of the problems.
After choosing a map, you'll have a long list (21 kB) of monsters. Choose one and click on Add to/remove from button. If it isn't already on the list it will be added to it, and if it is on the list it will be removed from it.
The records there are reflected in the monster lookup, so if a monster is added to a map, this location information will be displayed on its lookup (click on the names in the popup window from >Monsters<).
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