Running updates on already created images

Hi gang, I have a question. I have some images that were created with instaDMG. Is there a way to update these images without re-running the instaDMG script? To by hypothetical, say that 10.5.3 comes out today. Of course I could put the 10.5.3 updater in my AppleUpdates folder, run instaDMG and re-create my image. But, is there a way that I could take my already created ASR image with 10.5.2 on it, and run the 10.5.3 update and target my 10.5.2 image? I imagine it would mean mounting the image, running the update on it, then re-packaging everything up again. Has anyone done this? Can anyone share code?