So I want to add a file in /boot/ of my current saved HVM but in order to do it in my case; I have to mount my saved iso and add file from there. Surely, I can look in filesystem of dom0 and edit the iso I gave my qube manager when I made the HVM no? Where would I look to access the iso?
Where did you save the file, what does it say in the Qube Manager?
That will tell you where to access the iso.