We're going to have a "save as" button that lets you edit your code in an external editor. It'll be in the next release. See
http://labs.toolness.com/trac/ticket/274 for details. It's not as good as the IAT integration but it should suffice for now.
If you are interested, you could work on a whole bunch of things regarding the command editor like the syntax highlighting, tabs, etc. (
http://labs.toolness.com/trac/ticket/251)
- Abi