Did u follow Plailect's guide to install A9 and Luma?If so,u've already set the payloads!
If not,see https://github.com/Plailect/Guide/wiki/Part-5-%28arm9loaderhax%29 ,follow 12,15 and 17 in Section I - Preparatory work.
Then u could hold Start on boot to launch Decrypt9,Y on boot to launch...