I GOT IT!!!
OK, I thought, the metal is too hard to drill out without harder tools. BUT, even the hardest steel can be ground away with an abrasive.
I to a small cylindrical stone on a dremel, ground a hole down till I could see the notches on the easy out, then just tapped it out.
Then took progressively larger bits, 1/64th at a time, and drilled out the liner, on the last one, the whole thing just spun out.
Hopefully, I haven't destroyed the integrity of the hole, and can retread.
The next issue, is that the breechplug, splits the liner right in the middle. Lots of fouling still in there. Will probably replace the plug, and try to figure a better way to install the new liner. (i.e. groove the plug, or some such).
(At least I think I saved the barrel.
Thanks for all your responses, now any ideas on the new liner???