Yes, you need to copy them to a computer first and the use GTTOOLSHARP to extract them. Then once extracted, you can modify the events to your hearts desire. You do need to repack them again with GTTOOLSHARP once you're done. What I'd always recommend is keeping the original files saved as a backup in case you break something. Happens to the best of us.
When I'm modding I do it bit by bit, check it works, then a bit more, check it works etc. I always save the original files and the last couple of versions of my mod so I can step back if I need to.
You can download GTTOOLSHARP and find some instructions here:
https://nenkai.github.io/gt-modding-hub/ps3/basics/volume_system/#understanding-pdipfs
You need to run command prompt from the folder the GTTOOLSHARP.exe is located in, not from your desktop.