If you want your custom button on a product page, you can simply do this by calling the link_click() function, as Hello Retail already have the meta-data for this specific product. This will trigger the wish list panel to slide out and add the product to the wish list.
// Custom event to trigger the wish list panel to slide out, and add the current product to the wishlist.
If you want to show the wish list without adding the current product, you can use show_panel(true) instead.
// Custom event to trigger the wish list panel to slide out, without adding a product.