自定义设置omnaith-auth0 gem

Question

我正在使用omniauth-auth0 gem在我的应用程序中使用auth0 starategy。现在，我想进行自定义设置，例如（对于Twitter）：

  request = Rack::Request.new(env)
  user = User.find_by_subdomain(request.subdomain)
  env['omniauth.strategy'].options[:client_id] = user.consumer_key          # if using omniauth-oauth2
  env['omniauth.strategy'].options[:client_secret] = user.consumer_secret   # if using omniauth-oauth2
  env['omniauth.strategy'].options[:consumer_key] = user.consumer_key       # if using omniauth-oauth
  env['omniauth.strategy'].options[:consumer_secret] = user.consumer_secret # if using omniauth-oauth
end

use OmniAuth::Builder.new do
  provider :twitter, :setup => SETUP_PROC
end

不幸的是，对于auth0来说这是行不通的。如何在oomniauth-auth0策略中做到这一点？