Hi there - the problem here is that you can only add a new puzzle source for crosswords that:
1. Are distributed with the "Across Lite" puzzle format. 2. Are distributed with a predictable, date-based URL pattern.
As far as I know People Magazine does not distribute a puzzle in the "Across Lite" format, so I don't think it will be possible to solve those puzzles in Black Ink.
It would be worth a try to send a message to People Magazine asking them to distribute their puzzles in Across Lite format.