Actually, I don't feel particularly qualified to write up a cook book on dungeon scripting. I doscovered something new while trying to do so. And so the word of the day is ``BoundedRandom''.
Just try copying and pasting the Gloomy Caves plugging it into the dragon tower and making changes to that for starters. That will help you learn the what bits do what.
Once you're satisfied with your ability to manipulate the script, then you can script from scratch (still a lot of copy and paste).
While you explore, keep a paper notebook of what you're doing, and write down your ideas. Be open to the possibility it may be a long process. I spent about 6 months sourcediving and squinting at the code before I began compiling :/
Also, if you get stuck, I can help
Start by changing the grassy ground in New_Attnam to sand!