Adding files to an .img

Hey, Im new to this board…and just had a question.
I extracted an image of Diablo II Expansion with Clone Cd and it works…but the quesion I ask is…can I add a file to the .img
I want to add the latest update for Diablo right onto the cd…is this possible.
Thanks for the help if you know how.

Since this cd uses sub-codes as part of it’s protection, the burnt image won’t work if you add files to the image with, say winiso, before burning (because the subs won’t match).