Here's what I did -- it's a roundabout way, but I couldn't find any other solution. I made a separate folder under my theme called 'woowidgets' and then copied over the ones I needed from the '/plugins/woocommerce/widgets' folder.
Then, I copied the function that loads/initializes the widgets from the '/plugins/woocommerce/widgets/widget-init.php' file. I had to modify the naming conventions so that I didn't try to make a second call to that same function.
Finally I updated my theme's functions.php file to include the new initialization string and include to reference the widget file within my newly created widget folder. Now I'm free to modify that widget as a custom file and it will appear on my widget screen in the UI alongside the original Woocommerce-supplied one. I'll just drag my widget into the sidebar instead. Here's more or less what my structure looked like afterwards:
functions.php
include_once('woowidgets/widget-cart.php');
function woocommerce_register_widgets_CUSTOM() {
register_widget('WooCommerce_Widget_Cart_MJ');
}
add_action('widgets_init', 'woocommerce_register_widgets_CUSTOM');
/woowidgets/widget-cart.php
I replaced any instance of 'WooCommerce_Widget_Cart' with 'WooCommerce_Widget_Cart_CUSTOM'
I also edited line 26 '$this->woo_widget_name = __('MY CUSTOM CART WIDGET', 'woocommerce' );'
Lastly, I edited line 31 to give the cart a new name:
/* Create the widget. */
$this->WP_Widget('shopping_cart_CUSTOM', $this->woo_widget_name, $widget_ops);
It all seems to be working pretty well, just a lot of copying, pasting and editing. let me know if it works out for you if you find a better/cleaner solution.
