Never mind
After a lot of head scratching and some choice words, it turned out to be easy as pie. I was afraid I might break something off, but since most things I know on the car either snap off or twist off I decided to give it a try. The hands-on portion took maybe 5 minutes, but the thinking part was 10 times that. Oh well, I'll know exactly what to do next time.
So there, I answered my own question
BTW, the best tool for getting the tail light assy out was a plastic knife and fork
(sturdy plastic).