How to add a custom language highlight?

[fr1g]

The part of docs about customizing built-in shiki is still confusing... So I tried to copy the code provided in shiki's documentation and import it directly into vite's config, the compiler said that I cannot use async in top-phrase of CJS, but except that I don't know how to let shiki know my custom language while vitepress starts up.

BTW the custom language I'm trying to add is SkriptLang, a script language for Bukkit Minecraft Servers.