How do I configure an alert, for a specific Instance name?

Do you have perhaps a specific example of instances (with made up data) for what you are looking to do?

For example if you want to set a count threshold of 5 for event id 1234, 2 count for event id 4321, and 10 for everything else. One option is to create special Datapoints that only deal with those event ids. like having Datapoints called "CountIfEventId1234" and "CountIfEventId4321" that always return 0 unless you have event ids 1234/4321. You an then set global thresholds for these special datapoints separate from the more generic Count. This wouldn't be all that great if you have a ton of exceptions though.