No, I don't think so.
I tried to figure out exactly how it all works out, but I didn't.
I looked around in a decompiler, but couldn't figure out when exactly the cms is clearing the shopping cart and making the order.
My guess is that you need a custom provider, or to customize the DocumentWizardManager web part to do that.
In my case, I didn't need the payment form at all, so I just load it and redirect to my 3rd party payment form.