Thanks Andrew, for pointing me to this and GRE-639 as something to look at.
I thought to also put the useful pointers you gave in here, for easy reference / record keeping.
> Both deal with the new groovy test case wizard. The solution for both of
> them will either be to override methods from the superclass and use
> reflection to access private fields/methods. Or, if it gets too ugly, you
> can rewrite the new test wizard by copying code from its superclass and
> making all the changes you need.