I bet the BMBF (see: we don't need no stinkin' beer gun thread, top of forum) would work also. Could even use a bigger stopper to keep the fill slow and steady. Anything that fills from the bottom would suffice though.
This new Growler filler doesn't have a tube to go over the faucet. It has a metal fitting that goes inside the faucet. Its under 10 bucks at Draft Warehouse ( http://www.draftwarehouse.com ). Look under Tools and Fittings .
Let me know how it works if somebody gives it a try !