How to add files to a disk image

You would need to use hdiutil from the command line (Terminal.app) with the -shadow option to mount the read-only filesystem to read-write. You would then need to convert the shadowed filesystem to an ISO file (with Disk Utility.app or hdiutil).

Something like:

hdituil attach original.cdr -shadow ~/original.shadow -readwrite

... make the additions, and then...

hidutil makehybrid -o new.iso /Volumes/original -iso -joliet -eltorito-boot /path/to/boot/file

... or something like that. I don't know much about how the XP install media is laid out. Make sure that you are properly licensed. It'd be a crying shame to spend a few hours working on it only to get sued for copyright infringement for your troubles.

Moritz,

I think you'll need to create a new disk image.

Move all the files you want on the disk to a new folder and then use Disk Utiltiy to create a new Disk Image.

Matt