http://ngwclub.com/forum/viewtopic.php?f=47&t=25983
Here's a recent photo of the engine:

Excuse the rust and dirt, this is a daily driver (during Illinois summer at least).
The crank signal for the ecu is picked up from the single ballast resistor feeding the waste-fire coils. This gives one ignition pulse per 180 deg crank, just like a 4 cylinder distributor with single points. Could have used the cheaper megasquirt I with this arrangement, but the microsquirt should allow full ignition control, which is on the agenda for this winter.
Since I had well tuned maps developed for the other ecu, was able to convert them over to microsquirt format and have some reasonable maps to start out with. Winter hit before I could do much datalogging, but they seemed ok (the translated maps and enrichments are included in the link above). The other ecu had full sequential fuel, but the batch fire microsquirt seems to idle and run just as well.