As I was writing my request I relised that it was going to be difficult for people to disseminate the information - it was also late!
Ghosts Bootwizard can creat boot disks based on one of three OS - PC DOS, MS DOS or Win PE. In my case I have chosen MS DOS (PC DOS won't boot on the old PCs I need to create the image disk set for, and Win PE takes up 140MB of a CD plus take around 10 mins to load. To create an MS DOS bootable image you must first supply a floppy disk with the MS DOS System files on - in this case I used a Win 98 start-up disk.
You then have several options as you go through the boot wizard which allow you to create different boot possibilities (i.e. floppy, USB, Network CD etc). I want to create a CD image but here you have two options - the "Standard Ghost Boot Package", and the "CD/DVD startup boot package with Ghost".
The first uses some kind of CD drivers that enable you to see a CD/DVD drive in Ghost's open file dialogue box, but no DOS based drive letter is assigned. The second uses standard MS DOS drivers (such as MSCDEX) in which drive letters are assigned. In both cases an ISO image is created that contains a single OSBOOT.IMG file. This IMG file appears to be a HDD emulation boot image and is sized at about 25MB. When the CD boot, the drive letter C: is assigned to this image emulation and all files stored within it can be accessed.
What I'm trying to do then is create a CD set that boots from the CD then loads Ghost (this is all achieved trough the bootwizard) then starts to initiate the Image restoration to the HDD, so I would like to include the first part of the Ghost image to be restore somewhere on the Boot CD. I can try and add this Ghost (GHO) image file (600MB) during the Bootwizard process, but the the bootwizard tries to add this to the OSBOOT.IMG file - and 600MB into 25MB don't go! Ideally the GHO file would be included in this IMG file, but I'm not sure if this is possible even with third party tools, to expand the IMG file larger than it is currently set, but I may find difficulties with later parts fo the GHO image that will have to be stored on seperate CDs.
I could add the GHO file into the standard ISO image - which is effectively what I'm doing with the ImgBurn "Create Image File" option. I would like to automate the image restoration so I really need to use the Boot disk option that allows MSDOS to access the the CD - I'm not sure how to script this unless the CD has a drive letter assigned. Of course, there is the need to use multiple CD (the machines in question only have CD drives not DVDs).
I writing this I see that the only option is to create a DOS boot image that has assigns drive letter to the CD drive, then I can use ImgBurn create bootable image from the IMG file out of the original ISO, then add the first GHO file and re-create a new image.
I'm cheating slightly as ImgBurn cannot seem to extract the IMG boot info from the ISO CD, so I have to use another tool, but I'm trying to stick with free to use tools (i.e. NOT use things like UltraISO, MagicISO or whatever) which I think will do the same job.