The question seems pretty clear to me. The simple breakdown of the question is that he needs to use an COM object model, which is part of ESRI's software, but that doesn't matter. The important part is that the interfaces only implement IUnknown(single interfaces). As opposed to interfaces that implement IDispatch and IUnknown(dual interfaces). IDispatch allows for the user to get type information at run-time, which I believe is needed for perl to use COM objects.
My guess is the Script adapter is a dispatch layer on top of the IUnknown interfaces.
I don't know of any way to do this in perl.
Also, if you're not a COM/Windows guy, you probably shouldn't be responding to a COM question. Using a very common term such as "dual interface" is perfectly acceptable, because anyone whose used COM before knows what it means.