ModAPI.addAPICallback("KernelExtension", function(api) {
    // api parameter is the KEX namespace in KEX API documentation
});

// launcher.js

ConfigureMultiplayer({
    name: "KEX-Dependent mod",
    version: "1.0",
    isClientOnly: false
});

ModAPI.addAPICallback("KernelExtension", function(api) {
    // checking if getKEXVersionCode function exists in API object, then calling it and checking if the version is applicable for your mod
    if(
        typeof api.getKEXVersionCode === "function" &&
        // in this case checking if the version is 3.0 or higher
        api.getKEXVersionCode() >= 300
    ) {
        // launching the mod adding the API object to its scope
        Launch({ KEX: api });
    }
});

// then, in your mod's main code, you'll be able to access the Kernel Extension API using the KEX variable (same as in documentation, so this way is very convenient for TypeScript developers using KEX API declarations)