I think the help shows how to pretty well using ActiveX.
I think I tried it once for kicks and it worked, but I didn't save any code.
Anyway, the HATCHEDIT command makes it easy anyway.
But today I was altering geometry to get proposed impervious lower than existing.
I had all the loops on the same layer "IMPERV-PL" so I just used my GripLayer and the -HATCH command to rebuild the hatch and then get its area. It wasn't painful at all except that I learned that if an outer loop touches itself, the area property is not applicable or available. So I just cheated and stretched a few points away from others. The reviewers and even my boss wouldn't be able to see anything awry over 19+ crooked acres, even if they had AutoCAD.
