How do I add a new antenna to the HFSS Antenna Design Kit ?

I believe the HFSS Antenna Design Kit (ADK) can be extended by adding your own code, but does anyone have any instructions on how to do this? For example, lets assume I want to be able to design a folded dipole to have a specific impedance. One can achieve this by having the two sides of the dipole of a different diameter, and there are formuals which give you at least approximate ratios to use. So in principle I have the maths to design the antenna. But how could I add that antenna to the ADK?

What's the chances of this post appearing only one, and not twice as so often seems to happen on this forum recently? Let's see!

Deborah