update testing steps with new code

Author: senadir

docs/testing/releases/600.md

@@ -25,11 +25,11 @@ Zip file for testing: [woocommerce-gutenberg-products-block.zip](https://github.
 
 ### Pass billingData to canMakePayment and debounce its calls ([4776](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/4776))
 
-- Add this code somewhere (you can try `assets/js/base/context/providers/cart-checkout/payment-methods/use-payment-method-registration.ts`):
+- Add this code somewhere (you can try `assets/js/base/context/providers/cart-checkout/payment-methods/use-payment-method-registration.ts`).
+- If you can't edit files, install `Custom CSS & JS` plugin and insert this code:
 
 ```js
-import { registerPaymentMethodExtensionCallbacks } from '@woocommerce/blocks-registry';
-registerPaymentMethodExtensionCallbacks( 'woocommerce-marketplace-extension', {
+wc.wcBlocksRegistry.registerPaymentMethodExtensionCallbacks( 'woocommerce-marketplace-extension', {
 	cod: ( arg ) => {
 		console.log( 'checking COD' );
 		return arg.billingData.first_name === 'Alexandra';
@@ -46,15 +46,10 @@ registerPaymentMethodExtensionCallbacks( 'woocommerce-marketplace-extension', {
 - As the previous step, paste this code somewhere:
 
 ```js
-import {
-	registerExpressPaymentMethod,
-	registerPaymentMethodExtensionCallbacks,
-} from '@woocommerce/blocks-registry';
-
-registerExpressPaymentMethod( {
+wc.wcBlocksRegistry.registerExpressPaymentMethod( {
 	name: 'expressMethod',
 	edit: null,
-	content: createElement( 'div', {}, 'My express test method' ),
+	content: wp.element.createElement( 'div', {}, 'My express test method' ),
 	canMakePayment: () => true,
 	paymentMethodId: 'expressMethod',
 	supports: {
@@ -67,7 +62,7 @@ registerExpressPaymentMethod( {
 - Add this code now:
 
 ```js
-registerPaymentMethodExtensionCallbacks( 'woocommerce-marketplace-extension', {
+wc.wcBlocksRegistry.registerPaymentMethodExtensionCallbacks( 'woocommerce-marketplace-extension', {
 	expressMethod: ( arg ) => {
 		console.log( 'canMakePayment expressMethod' );
 		return false;