Custom meta boxes for custom post types

I’m using the following two lines and 2 functions to enable a custom meta box for posts – is it possible to enable these for custom post types?

add_action('admin_menu', 'my_add_custom_box');
add_action('save_post', 'my_save_postdata');

Post types have been registered with code like so:

register_post_type( 'projects', array(
	'label' => __('Projects'),
	'public' => true, 'show_ui' => true ,
	'supports' => array('title', 'author','editor','excerpts', 'custom-fields', 'revisions', 'comments' )
	)
);