How do YOU debug a Scala program?

I mean YOU as in the person posting the Answer :) Please answer only from personal experience, not from stuff you've heard or read on the Internet. You should not believe everything you read on the Internet, especially tales of complex open-source software configurations that actually work :-)

The are many Java tools which claim to support Scala in some way or another, but I have so far struck out in trying to get any one of them to actually let me set a breakpoint in Scala code and step through it. These are big, major open-source IDEs I'm talking about here.

The main problem in getting a debugger to work seems to be the "version hell" with fast-changing IDEs, Plug-Ins, JDKs, and the Scala language itself.

Hence, the more detailed re-statement of the question is appropriate: What is the exact version number of the IDE, Plug-In, JDK, Scala, and even Operating System, that you are successfully using?

My question is related to this one, but wider in scope: http://stackoverflow.com/questions/2272705/how-to-debug-scala-code-when-outside-of-an-ide

Thanks