Copying files to a Linux bootable ISO

I know it sounds the simplest thing you can do but not really right now.

Goal

My goal is to be able to do file operations without causing problems for a bootable ISO, since the builtin ISO reader (in an Ubuntu VM) seems to make it unbootable. As I rename a file in a bootable Linux (Ubuntu/Linux Mint) ISO with the builtin program, I can't boot from it using an VM.

Question

Is there something from the command line that I can do? I've tried using mounting the ISO but it's read-only.