I don't know for this specific model, but the taco is usually driven off the "-"ve side of the coil, now you have 3 coils,so they will each fire 1/3 the number of times.
What you may be able to do is take a pulse from each coil, run it through a set of 3 diodes to stop interference and into one wire and then use this to drive the taco.
I don't know if this will work but I can't see why it wouldn't.
Worth a try for $1.00 worth of parts.