Slightly OT - but what's the process for training an LLM to author a new language like this proficiently? I ask because I have my own language I maintain, and

Slightly OT - but what's the process for training an LLM to author a new language like this proficiently? I ask because I have my own language I maintain, and we're currently prompt-stuffing to get LLM's to author it - but I wonder what type of training set you'd need, and what base image one would use to fine-tune a model, and how effective it'd be?