I finally got Falcon to compile and run BasicTests successfully using the "old codegen". BasicTests is the test that runs when you run "ant checkintests". Next task is to get it to run with the –mxml.children-as-data flag. After that, I'll be trying to get my internal customer's app to run. Far off is getting BasicTests to run without Flash because we'd need to have JS versions of all of these components, but getting this far means that Falcon's MXML handling is in decent shape.
Thanks to Darrell Loverin and Gordon Smith for code and advice. -Alex