Well, the abscess *did* open up on the outside! Three cheers to Shelagh's wisdom! And thanks for posting all those photos of Twiggy's abscess, it helped a lot to get a sense of what was going to happen.
Basically, I could tell that some of the skin on the very tip of the bump died off a couple of days ago (what I guessed would form the scab). I kept a very careful watch on it, knew there was probably a hard pus ball right underneath the scab (a lot like Twiggy's looked like from his ear). Tonight I brought the girls out to say hello to Dad, and noticed that when Cera groomed there was a titch of pus coming out the bottom.
Ran off with her to the basement, tossed Ducky into the CN. Set up on the washing machine (easily sterilized) with two layers of nappy blankets, a Ziploc tub of lukewarm water, Q-tips, a syringe, and lots of gauze. I didn't take pictures because *my* nerves were shot - more than once I really wanted to have a drink, but figured I needed to keep the whole area sterile.
Anyway, the scab is opened up along the whole bottom half - there's still hair on it, which kind of makes it hard to see inside most of the time (except right after flushing it). Her whiskers seem largely unaffected, the tissue underneath after flushing was sort of reddish and raw, but the edge looked very good. I imagine that she is happy the pressure is gone, and I know she's clean since there's a tiny bit of plasma/blood discharge, so she won't eat the yicky stuff. She is still grooming her face, albeit carefully. I'm not sure if the scab will come off on its own or if I'll have to soak it again in the morning - we'll see, but she was fed up and I'd done all I could conceivably do for tonight.
On an interesting note, not that this is news, she's a canny little bugger. She seemed to notice whenever I would flush her abscess or do things to it, I was using my right hand, and kept her still with my left. So after a few rounds, she would whirl around and face me resolutely, and refuse to wander anywhere that left her tail facing me (so I could keep flushing). I think she figured out I'm right-handed!