[Plugin: Multiple Post Thumbnails] Restrict MPT to specific post

Hi, sometimes i need Multiple Post Thumbnails only on specific pages. I don’t want the metaboxes to appear when editing other pages. My two questions are:

(1) Is there a way to restrict MPT to a specific post_id?
I tried the following in functions.php, but the media-upload dialog is missing the “set secondary image” option.

if ($_GET['post'] == '85') {
if (class_exists('MultiPostThumbnails')) {
    new MultiPostThumbnails(array(
    'label' => 'Secondary Image',
    'id' => 'secondary-image',
    'post_type' => 'page'
    )
);
}}

(2) Do you consider adding more filter options to the plugin?
E.g. WpAlchemy has a bunch of filter options which are very handy like 'include_post_id' => 85