Norbs has the single channel "Universal" version for distributor ignition.
The "Vampire" version connects to the coils of a COP or waste spark ignition. Control wires connect from the unit to the coil negative signal of each coil. The "control" wires are both inputs and outputs, so no wires are cut or intercepted.
Individual cylinder knock retard is no problem with a waste spark system. For example, say cylinder 1 of the "1-4" coil is knocking. Software calculates the amount of knock retard to apply the next time this cylinder is on its compression stroke. Software "knows" that this cylinder won't be on its compression stroke again for two more revolutions.
In one revolution, cylinder 4 will be on its compression stroke, so it will not be retarded unless it was was also knocking.
When cylinder 1 is again ready to fire on its compression stroke, software looks up the calculated retard value for that cylinder and fires the 1-4 coil. Cylinder 4 is on its exhaust stroke, so "retarding" it has no effect on power.
For reference, see the four channel waste spark installation for '96-'98 Ford:
http://www.jandssafeguard.com/Instructions/Vampire_Instructions/4ch8cylVampire.pdf