Can someone guide me on how to modify this WMS PDF (packing list)?

Could you elaborate more on what exactly you need? Are you needing a certain section modified to look different? Are you wanting new information added? Are you trying to just find the form itself, or you're unable to edit it?

That PDF is generated through a WMS suitelet that is locked, and I am looking for a way to modify it to change its appearance.

If it is a suitelet, try to figure out how it is getting the template to use. It might be a HTML file in the file cabinet

It is a Suitelet that generates the template but it is blocked

oof, hope some WMS dev didn't have to do all that in-script...

That's some......bad code.

ahh. yep.. that's s$%t. One has to ask... why would any dev do that?