While waiting for an expert to chime in, here is where I am so far.
I took that old vb sample and cut out nearly all the code so it basically just returned the word "Attachement" and it showed up as an available data type (and that's about it).
Now I spun off a similar C# version and that just adds my new choice to the avaiable data types. Yeah!
However I've no clue yet how to add the 'form' part to have it really work.
In my case want to put a dropdown "Department" list on the form (that I'll populate and filter to only offer departments the user has access to), the list view will simply show the selected department for the record.
So first/next step; how to I make this thing put a simple drop down list on the form? (I'll work on fancy filtering later)
If I can get anything acutally working I hope to share a sample here.