We currently don't support proxy servers with ActiveMerchant, but you
should be able to hack support for it in
lib/active_merchant/lib/posts_data.rb
Then you could probably add some sort of inheritable accessor to the
base gateway class in lib/active_merchant/billing/gateway.rb that sets
the proxy server.
--
Cody Fauser
http://shopify.com - e-commerce done right
http://www.codyfauser.com - blog
http://peepcode.com/products/activemerchant-pdf - ActiveMerchant PeepCode
http://www.oreilly.com/catalog/rjsrails - RJS Templates for Rails