You can do this for tags. Lock the view, then use the "Tag all" tool instead of trying to tag the individual objects. Revit will tag the objects at the center, and you can then move the tag.
You will want to set the tag to "Free end" as you can see from the wall on the right in my photo, the leader goes to nothing when turned on.
Keynotes lack this feature, so adding user or element keynotes I haven't been able to make work. Material keynotes, however, worked just fine and were able to find the object faces.
But it's a pity that tagging with keynotes is not totally implemented, only keynote tags by material or by user are allowed.
Here, in Spain, its common to use keynote files linked to external databases generated from QTO programs like arquimedes ( http://arquimedes.cype.es/ ) or presto ( http://www.rib-software.es/presto.html ), and tagging by element in a exploded view would be a great improvement.