Divert first web request after policy allow to a URI

More details. APM is doing the auth, but we need to send the credentials over to this external server (SSO, essentially). I don't get any data back, but the user will be thrown on the floor if they haven't or don't accept the T's & C's, and redirected back to APM if they have. So I need a way to do a forms post to this external page. If I set up an SSO profile (assuming that even works prior to policy "Allow" ending), then I can't use it for the apps behind the portal, since you can only have one SSO profile on a policy.