I'm not sure what it is you are trying to do, the only way to get around it is to extract that .iso file you have into a folder on your PC so it is just a collection of files. Then add the Dario X patch and it will be a simple file overwrite.
Use C-Xbox Tool to the recreate the .iso with the new files enclosed and burn.
Use C-Xbox Tool to the recreate the .iso with the new files enclosed and burn.