OK, ready to report on first batch of 'cider'. Short version: refreshing and I'll try it again.
For those of you with patience, the full report follows.
The 'cider' seems to be made like miel (if I understand miel correctly). Chief differences appear to be that some water and spices are added at beginning, it is decanted earlier, and the yield is higher.
I loosely followed a recipe in One Cacao Tree, by Raven Hanna. In addition to providing steps for small-scale chocolate making, she has quite a few cacao recipes for products that don't require all the preparation steps needed for chocolate.
Roughly speaking: Almost fill a sterile two-quart mason jar with pulpy seeds, add spices, cover with some water, loosely close and then wait about 3 days. If no mold, decant.
I observed the expected yeasty reaction -- lots of small bubbles. After 3 days decanted about 1 1/2 cups of lightly-colored liquid. Chilled in fridge. Result was refreshing, tangy and bubbly like a cider just going hard. Unfortunately, the 4" long piece of cinnamon that I had put in the bottle did overwhelm any subtler flavors that may have been hiding.
I'll be trying it again, with less cinnamon, some time later. And I might be motivated to try something with the under-fermented seeds, which I just tossed away the first round.
-- Chris