Hey there,
basically, you will have to create a plugin for DeepSeek using the plugin editor. Sadly there's no tutorial yet. I'll see if I can build such an plugin for you. DeepSeek has got an ChatGPT compatible API endpoint, so it should be doable.

Btw: There's a new version, called "AI Game Master SE-3". It only supports groq.com at the moment, which does also provide a DeepSeek model. It is way easier to setup than SE2.  Please drop me a note if you want to try it and i can send you a beta release.