OK, I've done a little research and can be more helpful now. The problem is that an OS X install DVD isn't a straightforward HFS disk, it's a hybrid between that and an ISO disk. If you look at the device selection screen on HFS Explorer it says (to the right of the "Device" label) "(hybrid CD+ROMs with both HFS/+/X and ISO filesystems won't work)". That explains your problem.
The good news is that I have found a program that will do the job (it's commercial, but there's a 5-day trial); it's called
MacDrive. Once you have installed it, and rebooted, you need to go to "MacDrive 9 Standard/Tools/Change MacDrive options" in your Start Menu. On the "Settings" tab click the "Show Mac files" radio button under " Dual-format CDs/DVDs" and click "OK". Then put the disk in the drive (or eject and reinsert it if it's already in the drive) and open Explorer. Note that many of the files on the disk are hidden, so you will need to change the view options. (I noticed that having done the above HFS Explorer also sees the Mac version of the disk.)