I'd also like to be able to do what the OP describes. FYI, I haven't
tried it with Authorize.net, but I was unsuccessful in my attempt to
process this type of transaction with PayPal's PayFlow gateway and their
equivalent of DPM (transparent redirect...
The partial authorization itself is successful, right? And it's just an
issue with the extra responses for "Requested Amount" or "Balance on
Card" fields?
