I had been using Custom Category Post order with great success, but then it stopped working, as did everything else I tried... My Post Order, Q2W3 Post Order, Custom Post Order etc... So I thought I'd try one of these older guys.
(Kapil, the author of My Post Order offered great assistance to me even though his plugin is not really digigned for this type of customization)
PostMash did not work either.
You need to add code to your template php files (index.php, category.php etc.) with this one for it to work, but that did the trick. Now I can have custome post orders by category, with posts that share categories having individual orders in each category... Yes!