Rails 2.3 + Devise + Omniauth

I am making one last-ditch request for help here, after spending the
entire weekend googling and yak-shaving with this combination.

I have a single-sign-on working perfectly with a Rails 3.1 Oauth2
provider and a Rails 3.0 client. Now, trying to duplicate that early
success with a Rails 2.3 site that also has to be a client, I have hit a
wall. Devise didn’t support Omniauth until 1.2 or so, but as far as I
can tell, 1.2 won’t run under Rails 2.3.

Can anyone point me to a solution? Otherwise I have to upgrade the site
to Rails 3, and I’m not looking forward to telling the client that she
has to pay for that on top of everything else.

Thanks in advance,