Hi Matt,

Ok, well, these are most of the steps that get called during finalization from the Continue URL

Order order = GetOrder(storeId, orderId);
IPaymentProvider paymentProvider = PaymentProviderService.Instance.Get(paymentProviderAlias);

IDictionary<string, string> settings = PaymentMethodService.Instance.Get(order.StoreId, order.PaymentInformation.PaymentMethodId.Value).GetMergedSettings(order.LanguageId);

CallbackInfo callbackInfo = paymentProvider.ProcessCallback(order, HttpContext.Current.Request, settings);

if (callbackInfo != null)
{
    order.Finalize(callbackInfo.AmountAuthorized, callbackInfo.TransactionId, callbackInfo.PaymentState, callbackInfo.PaymentType, callbackInfo.PaymentIdentifier);
}

SessionController.SetCurrentFinalizedOrderId(order.StoreId, order.Id);

string continueUrl = paymentProvider.GetContinueUrl(order, PaymentMethodService.Instance.Get(order.StoreId, order.PaymentInformation.PaymentMethodId.Value).GetMergedSettings(order.LanguageId));
if (!continueUrl.StartsWith("http"))
{
    Uri baseUrl = new UriBuilder(HttpContext.Current.Request.Url.Scheme, HttpContext.Current.Request.Url.Host, HttpContext.Current.Request.Url.Port).Uri;
    continueUrl = new Uri(baseUrl, continueUrl).AbsoluteUri;
}

HttpContext.Current.Response.Redirect(continueUrl);

This is just a code dump though as most of this is spread across multiple functions. Hopefully there is enough here though to piece together a solution.

Matt