Well the neck is off... I inspected the slot carefully, and could see it was not a real tight fit...searched around and found a real thin palette knife, and tried heating it, and working it into the slots down the side of the neck. This had worked for removing the fretboard, so I was encouraged... It was tight going, and I worked slowly, not wanting to split anything. I actually got the knife so hot, I had to hold it with welding gloves and vise grips, and it probably burned its way in as much as melting glue, but it did work. I applied mild pressure to open each seam as I inserted the knife. Since the neck is broken, I worked into it and away from the body side of the slot with the hot knife.
I cleaned up the pocket on my trusty milling machine, and the next step is to build a new bolt-on neck to fit the "custom" sized slot...a project for when I return to Canada from Yuma, and re-enter my man-cave.
Note to luthiers on this forum: don't faint yet! I actually didn't do any appreciable damage to the finish! There will be some edge cleanup, and touch-up with crazy-glue and nail polish, but I don't think there will be any ugliness to detract from the new bolt-on configuration...we'll see anyway!