M@nticore, you're in unchartered territory here! I think very few people have attempted to do what you're doing, so there isn't much knowledge going around. That's not to say it can't be done, but does mean you may have to do a lot of work to hook it up.
I suspect you'll need to find out what information the Microplex needs, and whether the appropriate sensors can be fitted to your engine.
One suggestion might be to use the ignition management from a Cinquecento/ Seicento? These were designed for the FIRE engine, so in theory you should be able to retrofit it to your car with less work than a Microplex meant for a different engine.
Alternatively, if you are thinking of turbocharging your FIRE engine, perhaps finding a Turbo ECU might be a better idea? They can be picked up fairly cheaply off Ebay if you look. You will however run into problems with getting the sensors to work, and as mentioned you need an RPM sensor that requires a certain number of teeth on the flywheel to function properly. You might get round this problem by adapting a flywheel meant from a Uno turbo engine?
The people you need to ask are Oldschool and Smokeme. Both have lots of experience with working with FIRE engines, and Smokeme has had considerable success with turbocharging them. I know Smokeme used a stand alone management system called 'Megasquirt', which from what I gather is programmable and mappable.
Other than that I don't know what else to suggest. I'm only used to playing with carburetors!
Chas