Kirk, did you try our plugin?:
http://elggdev.com/vazco_forum
With use of vazco_groupforum extension it should give you exactly what you need. You can test both on our test server at test.elggdev.com.
We're currently busy with projects so we can't help you with custom development although you should be able to set up threaded group forums simply by configuring those plugins. We can help you with support.
ps. GPL version of vazco_comments plugin which you tried is not supported for some time already.
what exactly do you need??
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