functions.php

<?php
add_filter('sharepress_supported_post_types', '__my_sharepress_supported_post_types');
function __my_sharepress_supported_post_types($types) {
  $types[] = 'bgmp';
  return $types;
}

add_filter('filter_sharepress_meta', '__my_filter_sharepress_meta', 10, 3);
function __my_filter_sharepress_meta($meta, $post) {
  if ($post->post_type == 'bgmp') {
    // maybe make changes to $meta?, e.g...
    $meta['message'] = "This is a custom message that overrides what is entered on the post editing screen";
  }
  return $meta;
}