Basic example of how to use the jQuery Validate library to display errors on the admin side of WordPress in conjunction with jaredatch / Custom-Metaboxes-and-Fields-for-WordPress.

admin.js

jQuery(document).ready(function($) {
  $('.cmb_id__prefix_layout_option').find('td').append('<div id="_prefix_layout_option_error" class="alert alert-error text-center"></div>');
	$('input[name="_prefix_layout_option"').addClass('layout_option');

	$('.cmb_id__prefix_thank_you_url').find('td').append('<div id="_prefix_thank_you_url_error" class="alert alert-error text-center"></div>');
	$('input[name="_prefix_thank_you_url"').addClass('thank_you_url');
	$("#post").validate({
		//debug: true,
		ignore: [],
		wrapper: 'p',
		rules: {
			_prefix_layout_option: { required: true },
			_prefix_thank_you_url: { required: true, minlength: 3 },
		},
		messages: {
			_prefix_layout_option: {
				required: 'You must select a layout.'
			},
			_prefix_thank_you_url: {
				required: 'You must enter a valid thank you url.',
				minlength: 'The URL must be at least 3 characters long.'
			}
		},
		errorClass: 'alert-error',
		highlight: function(element, errorClass) {
			$(element).addClass('error');
		},
		unhighlight: function(element, errorClass) {
			$(element).removeClass('error');
		},
		errorPlacement: function(error, element) {
			if ($(element).hasClass("layout_option")) {
				$('#_prefix_layout_option_error').append(error);
			} else if( $(element).hasClass('thank_you_url') ) {
				$('#_prefix_thank_you_url_error').append(error);
			}
		},
		invalidHandler: function() {
			jQuery('#publish').removeClass('button-primary-disabled');
			jQuery('#publishing-action').find('.spinner').css('visibility', 'hidden');
		},
		submitHandler: function(form){
			form.submit();
		}
	});
});

functions.php

<?php
//If you are running within a theme add this to your functions.php
//To load within a plugin add the following line to your __construct() and uncomment lines 5 and 12.
//add_action( 'admin_enqueue_scripts', array( &$this, 'add_admin_styles' ) );

//function add_admin_styles() {
    global $wp_query;
    if( is_admin() && $wp_query->query_vars['post_type'] == self::PAGES_POST_TYPE ) {
	    // Load validation & Admin JS for CPT-editor page
    	wp_enqueue_script( 'jquery-validate', plugins_url( 'jquery.validate.min.js', __FILE__), array( "jquery" ), '1.11.1', true );
	    wp_enqueue_script( 'admin-js', plugins_url( 'admin.js', __FILE__ ), array(), '2.1', true );
    }
//}
?>

post-type.php

<?php
$meta_boxes[] = array(
	'id' => 'basic_settings',
	'title' => 'Basic Settings',
	'pages' => array( self::PAGES_POST_TYPE ), // post type
	'context' => 'normal',
	'priority' => 'high',
	'show_names' => true, // Show field names on the left
	'fields' =>	 array(
    				'name'    => 'Layout Options *',
				'id'      => $prefix . 'layout_option',
				'type'    => 'radio_inline',
				'class' => 'layout_option',
				'options' => array(
					array( 'name' => '<img src="'.plugins_url( 'images/thumb-1.jpg" />' , __FILE__), 'value' => '1', ),
					array( 'name' => '<img src="'.plugins_url( 'images/thumb-2.jpg" />' , __FILE__), 'value' => '2', ),
					array( 'name' => '<img src="'.plugins_url( 'images/thumb-3.jpg" />' , __FILE__), 'value' => '3', ),
					array( 'name' => '<img src="'.plugins_url( 'images/thumb-4.jpg" />' , __FILE__), 'value' => '4', ),
					array( 'name' => '<img src="'.plugins_url( 'images/thumb-5.jpg" />' , __FILE__), 'value' => '5', ),
					array( 'name' => '<img src="'.plugins_url( 'images/thumb-6.jpg" />' , __FILE__), 'value' => '6', ),
					array( 'name' => '<img src="'.plugins_url( 'images/thumb-7.jpg" />' , __FILE__), 'value' => '7', ),
					array( 'name' => '<img src="'.plugins_url( 'images/thumb-8.jpg" />' , __FILE__), 'value' => '8', ),
					array( 'name' => '<img src="'.plugins_url( 'images/thumb-9.jpg" />' , __FILE__), 'value' => '9', ),
					array( 'name' => '<img src="'.plugins_url( 'images/thumb-10.jpg" />' , __FILE__), 'value' => '10', ),
					array( 'name' => '<img src="'.plugins_url( 'images/thumb-11.jpg" />' , __FILE__), 'value' => '11', ),
					array( 'name' => '<img src="'.plugins_url( 'images/thumb-12.jpg" />' , __FILE__), 'value' => '12', ),
				),
			),
            		array(
            			'name' => 'Thank You Path URL *',
				'desc' => 'This URL will be added to the site domain. Currently: ' . site_url() . '&nbsp;{plus this Path URL}',
				'id' => $prefix . 'thank_you_url',
				'type' => 'text'
			)
);
?>