Authorization protocols like OpenID and OAuth have been deliberately designed to require explicit user confirmation of access privileges. Any mechanism that bypassed user intervention would effectively be a security exploit. I'd recommend you save yourself time and frustration by accepting that you're not going to get around that interstitial authorization page.
For better or worse, scope authorization pages have become a well-established part of the modern web application landscape. Users these days routinely confirm authorization dialogs for Facebook, Google+, LinkedIn, and Twitter access without batting an eyelash. Your less savvy users may not recognize it as such, but using existing security mechanisms is a sign of greater professionalism than rolling your own.