Okay, well the more I think about it, I guess I can sacrifice the self-hosted join page if I have to.
As long as I can send the user over with minimal information and be able to get a proper yes/no the transaction is approved back - providers like verotel have username restrictions and their own password generation, so to get around that, we had to lie and make some fake password and map it back to our actual system username/user IDs.
I suppose as long as the transaction can be completed and send the user back with appropriate information (perhaps a custom form field with a digest that can be compared and validated) that works for me. Also a simple way to disable users when their accounts are up, etc. Verotel contacts the site at somewhat random intervals at night with rebill and cancellation information. If the site is down, it tries it 2-3 times, then it fails the transaction.
I'd prefer a pull method, so I have control of when I process the information. That is much more important I suppose than a self-hosted signup form. Forget I even mentioned that for now
