I gave it a set of DM rules (for example do not make decisions for me; do not cheat for me, etc.) but other than that I just asked it to DM the module for me. TBH I'm not really sure whether it is following the module, but at least it is following the undead theme.

It's a good question though. I know the gist of the story so I assume I'm still in the hook. The game went slowly as I don't have much time for it.

Something like: Prompt GPT4 with basic rules (in several batches) and have it create JSONL prompt-completion pairs to use as fine-tuning for GPT3. Freeze that model then continue fine-tuning it with a new set of prompt-completion pairs for each adventure module.