> So basically we will have a 2 page checkout if I understand this
> correctly.
Yes, you are right. We had to move entering credit card details to a separate page inside X-Payments. So it is going to look like this:
Step 1 (in X-Cart)
http://marketplace.x-cart.com/images/xcart_4_4_screenshots/step1.png
then redirecting to X-Payments
http://marketplace.x-cart.com/images/xcart_4_4_screenshots/redirecting2XPayments.png
then Step 2 (in X-Payments)
http://marketplace.x-cart.com/images/xcart_4_4_screenshots/step2.png