I take it you also tried the program mentioned in alooper21's response as well then? I only ask because it would be beneficial to others with the problem in the future if you mention what didn't work for you so they don't waste their time. Hopefully someone finds software that isn't junk and can accomplish the task eventually.
Actually, I haven't tried UltraISO because it's paid. I only used free software.
By the way, I tried CueTools to extract the audio tracks from the image provided by GOG but couldn't make it work yet. If I do, I'll probably start a new thread with the procedure.