Alteration Q: Waist Stay, where do I stop the boning an Sewing Machines Parts and Sales in Los Angeles

I’m trying to make a waist stay for this dress. http://sewing.patternreview.com/Patterns/75108
The lining goes past my waist, and the instructions for the boning extend through the lining. When attaching the waist stay, should I shorten the lining and boning, or just attache the waist stay to the middle of the lining?
TLDR: what’s the best way to attach a waist stay to a lining and boning that’s longer than your waist?