Reply to my own post: after N tries, with a significantly high N, it works now. Why it did not before and it does now remains a mistery. oscThumb 1.1 + moreimages 'old' 1.4.3 + the popup_image files from the same contributor's imageMix work perfectly, after a few tries. Thanks!
I tried both ImageMix and oscThumb 1.1, I can't seem to get the actual option in admin to turn the features on: could someone help? I copied the files into my OSC directory, ran the database modification, but the category is not there. Help would be appreciated. Thanks!