OK. Loaded the standard autonooter custom ROM (http://theunlockr.com/2011/02/06/how...he-nook-color/
) onto my rooted Nook Color.
I *think* it worked - ROM manager said the install was successful, but I never did get the little notice in the bottom left hand corner of the screen like I was expecting. And everything looks and acts precisely the same way as before, which actually was what I had hoped for...
I hope I'm safe from the update now.