I don't think the 5 Number Summary can be customized, but starting in JMP 17 you can make a custom annotation using the Caption Box element and selecting Location...Axis Table (Pic below). You can also choose the location as Graph Per Factor to mimic the 5 Number Summary look.
![Jed_Campbell_0-1677267063702.png Jed_Campbell_0-1677267063702.png](https://community.jmp.com/t5/image/serverpage/image-id/50478i83100093C1CC0FC3/image-size/medium?v=v2&px=400)