WordPress – Override woocommerce files from includes folder

I had the same problem except with add-to-cart.js. Simple solution is to DEQUEUE the woocommerce script and ENQUEUE your replacement. In my case I added the following to my functions.php:

wp_dequeue_script('wc-add-to-cart');
wp_enqueue_script( 'wc-add-to-cart', get_bloginfo( 'stylesheet_directory' ). '/js/add-to-cart-multi.js' , array( 'jquery' ), false, true );

You would want to DEQUEUE the 'wc-add-to-cart-variation' script. I don't think you have to ENQUEUE with the same name, but I couldn't see a reason not to.

Hope this helps.

If you're using WordPress Version 4.0.1 and WooCommerce Version 2.2.10. You can use the following scripts:

wp_deregister_script('wc-add-to-cart');
wp_register_script('wc-add-to-cart', get_bloginfo( 'stylesheet_directory' ). '/js/add-to-cart-multi.js' , array( 'jquery' ), WC_VERSION, TRUE);
wp_enqueue_script('wc-add-to-cart');

It seems there is no override solution to your question. But you can add a brand new payment gateway simply extending the WC_Payment_Gateway class, in other words by adding another payment gateway.

Step 1

You can duplicate the file:

plugins/woocommerce/includes/gateways/class-wc-gateway-paypal.php

in your directory theme, change its name for convenience and include it in functions.php:

/*  Custom gateway class */
require( get_template_directory() . '/path/to/class-wc-gateway-paypal-custom.php' );

Step 2

This file holds the WC_Gateway_Paypal class which extends WC_Payment_Gateway. You can edit this file for your customizations.

Remember to change the name of the extender class:

class WC_Gateway_Paypal_Custom extends WC_Payment_Gateway {
    public function __construct() {

        $this->id                = 'paypal';
        $this->icon              = apply_filters( 'woocommerce_paypal_icon', WC()->plugin_url() . '/assets/images/icons/paypal.png' );
        $this->has_fields        = false;
        // Change the text in the way you like it
        $this->order_button_text = __( 'Proceed to PayPal', 'woocommerce' );
        $this->liveurl           = 'https://www.paypal.com/cgi-bin/webscr';
        $this->testurl           = 'https://www.sandbox.paypal.com/cgi-bin/webscr';
        $this->method_title      = __( 'PayPal', 'woocommerce' );
        $this->notify_url        = WC()->api_request_url( 'WC_Gateway_Paypal' );
    }

    //other payment gateway stuff
}

Give it a try, let us know if you get stuck! : )

UPDATE 06/13/2014

It's also useful to know that there's a filter that allows you to change the paypal image, so:

function paypal_checkout_icon() {
    // pls return the new logo/image URL here
    return 'http://www.url.to/your/new/logo.png'; 
}
add_filter( 'woocommerce_paypal_icon', 'paypal_checkout_icon' );