Hi Rob,
Very neat idea. I don't know that I would have come up with the Location concept for solving this quickly. 
So - Creating "100 birds" location under World is the right thing to do. Now, did you use the Checklist Editor to add the 100 birds to this new location? That is all you have to do. Then you can use the Reports window to print a checklist for that location and have the ones seen checked off.
But for a life list report to work, your sightings of those birds will have to be at that location or a descendant of that location. that of course won't work as it has no descendants; and I don't recommend adding all high-level locations as descendants. Wherein checklist reports are tied to the checklist data, life list reports are not. It is simply a count of species seen, based on the selected tax list, at the specified location and all descendants.
So, to me the simple solution is to use the Checklist report for the new location and have it check off the species already seen, at any location. This won't give you a count of how many seen and how many unseen, you will have to manually count them up, but those seen will be checked off.
Oh - there is another way. Create a new tax list which contains only those 100 birds - call it "100 Birds". Use the Taxonomy Copy feature on the Taxonomy Viewer window to copy those 100 birds from Clements over to the new tax list and now your life list report will work as will most everything else you want to do with those 100 birds. And you don't need the new location you created. I think that is what I would do.
Let us know,
Jeff |