Image Handler 2: How to "convert" to IH photo management?

I've got a ZC site under construction with about 200 products. I had uploaded images for all of these products before I installed IH.

Now, I want to use IH to manage the images, but in a few minutes of experimentation, I really didn't make any progress. If I use IH to designate a photo for one of my products that already has a photo loaded by ZC, I get a SECOND photo on the product page which is obviously managed by IH, as it has the hover effect, etc.

If I go in using the ZC product editing panel and remove the image managed by ZC, the image handled by IH goes away, also!

How does one take a site's images that were loaded with ZC and "convert" the site to let IH manage the images? I looked around for a tutorial, but didn't find anything. The IH part of this forum is pretty hard to use as it is all posted under a single thread.