Quite easy actually.
Code:
Untitled Trigger 012
Events
Time - Elapsed game time is 1.00 seconds
Conditions
Actions
Floating Text - Create floating text that reads Point at (Center of Region 000 <gen>) with Z offset 0.00, using font size 10.00, color (100.00%, 100.00%, 100.00%), and 0.00% transparency
Floating Text - Change (Last created floating text): Disable permanence
Wait 0.01 seconds
-------- OR --------
Floating Text - Create floating text that reads Unit above Tester 0018 <gen> with Z offset 0.00, using font size 10.00, color (100.00%, 100.00%, 100.00%), and 0.00% transparency
Floating Text - Change (Last created floating text): Disable permanence
You only have to use one way, but you will need the part after each, that will make sure that the text doesn't go away. Dunno if you need the wait if your making multiple ones, but its better to be on the safe side.