More progress! Five 10TFF modules are now wired as a "twisted shift register":

Now I just have to re-wire the LEDs to make only one of them shine at a time.

Well, the decoding is pretty simple... Except for one little detail of course.

Back in Another display option I proposed the following diagram:

But it doesn't work right. The actual wiring should be :

It's pretty subtle but it works. The reset state turns LED#0 on.