You don't need any special software. Mount the iso, edit the files/directory, make a new iso from the contents.
An .iso can be mounted loopback.
Look at 'LOOP-DEVICE SUPPORT'
Code:
mount -o loop file.iso /mount/point
It will be read only. So you'll need to copy the contents to another directory with write permissions. Edit the contents all that you want to.
Then make a new iso
Code:
mkisofs -R -J /path/to/files -o /path/to/output.iso
genisoimage -o output.iso -r -J /path/to/files/*