Problems with running testcase via Groovy script

Hi,

I've been reading through this:

http://www.soapui.org/Load-Testing/load ... ution.html

esp. the part that says:

The underlying TestCase is cloned internally for each configured Thread and started in its own context; scripts, property-transfers, etc.. will access a unique "copy" of the TestCase and its TestSteps which avoids threading-issues at the TestStep and TestCase level (but not higher up in the hierarchy

and I guess that the question that I'm trying to get an answer for is HOW does SOAPUI do what is described above, and, more specifically, how can the behavior described above be reproduced in a Groovy script-based controller test step?

Thanks,
Jim