In my theme, I needed metabox to select multiple posts from current posts. Here it's how I've done it:
In plugin directory/wordpress-creation-kit-api/fields I created new file called selectposts.php Here is code
For showing woocommerce products instead of posts, simply change 'post_type' => 'post' to 'post_type' => 'product'
And then in wck-cfc.php in plugin directory add 'selectposts' to the array on line 109 and 587
Hope it's helpful for someone...
It would be great if you could implement this feature to the WCK