You can do this for the entire meta box. Use the ID comment block parameter:
https://piklist.github.io/docs/comment-block-parameters/#id

id: 20, 32, 49

You can wrap the field in a PHP conditional statement. In future versions of Piklist this might not work as expected. It would better to place this field in it’s own meta box.

Here’s an example of conditional code:

global $post;

$pages = array( 20, 32, 49 );

if ( in_array( $post->ID, $pages ) ) {

	piklist('field', array(
		'type' => 'textarea',
		'field' => 'welcome-intro',
		'label' => 'Welcome',
		'type' => 'editor',
		'scope' => 'post_meta',
	));

}