that is it in a nutshell Nick, and just split up the original amplifier trigger signal pulse train into 2 alternating signals, obviously synchronised with the phase sensor.
This does mean that there is a limited coil on-time at high rpm (same limitation as the standard system has) - yes it will drive 2 amplifers and a distributorless coilpack, but part of the benefit of DIS ignition (ie large spark energy independent of rpm) is not realised.
There are some sideline issues to deal with regarding synchronisation at startup, since you don't know what position you are starting from. The logical way is to wait until you see a full cycle of signals to establish where you are, but that could mean 2 full revolutions of cranking before the engine starts... there are a number of points in the cycle where you can infer the engine position earlier, but it does add complication.
Increasing coil dwell adds more complication, as you can only do that by pre-empting the coil turn onpoint, the turn-off point cannot be moved as that determines the firing point ignition timing. It becomes rpm dependent and no longer can be treated as a straight logic function.

I suspect that some application or other incorporated DIS ignition drive, like I said before, the L8 pcb has unpopulated components positions corresponding to a secong ignition drive channel, but it comes from a processor port line which obviously needs to be driven by the main program to be any use.. I have'nt been able to find another application using L8 and DIS yet.. Any Lancia Integrale versions DIS?