Integration with Jetpack Publizice

you can see the declaration under events-manager/em-posts.php

I scoured the file and found register_post_type functions referring to EM_POST_TYPE_EVENT and event_post_type

However by dumb luck, I simply used “event” and it worked perfectly!

For anyone else that finds this thread, the proper code is:

add_action('init', 'my_custom_init');
function my_custom_init() {
    add_post_type_support( 'event', 'publicize' );
}