Music Files Of Dungeons?

I read some time ago (and re-read it recently) this guide about how to replace music with custom music in FFXI:

https://gamefaqs.gamespot.com/pc/555735-final-fantasy-xi/faqs/30728

My problem is that I dont understand that well about how to put custom music on dungeons. I get the concept: replace wind and similar sounds with music so it plays like actually background music, but on that list there are many that kind of are everywhere and, from what I understand, some are "localized" only playing on tunels or caves.

So for many time I though it was just a fool errant, but I realize in some private servers they actually have background music, so it must be possible.

Had anyone changed this? Whats the best way to approach without having some unrelated music sound randomly in some cutscene or place?

Thanks.