Need help with tuning amp. Using LOC and powered sub.

Good day everyone, I am looking for guidance on how I am to be tuning my subwoofer properly, it is an nvx powered sub and I am using an xlca2 since I am on stock head unit. I have ordered an oscilloscope and have watched the videos on how to use it to tune an amp.

I will be opening the powered sub box to access the built in amp.

I am just unsure how to tune it with the loc, I’ve tried searching but I just mainly find threads on tuning just the amp. Any help is appreciated on this subject. Thank you all who chime in.