I have a stash of old transparencies of the sort that you feed though the copier or laser printer to create an overhead projector presentation. (If you are old enough to remember like pre Powerpoint you know what I mean).
I make up the copy I want in my word processor, etc, and print straight onto these (acetates?).
I then tape them to the underside of my contact printer glass when I want the effect you are looking for.
I also use them to title head shots with the actors name and agent when shooting with a dark background.
If I have a white background surround in the print, then I make a negative of the transparency with lith sheet film, and then use this as a second exposure to print in the black text. I have found that the black from the copier when I print reversed text from the word processor does not have sufficient DMax to not have to resort to changing multigrade filters for the second exposure, which is a PITA when printing a quantity of the same image.