He means on a switch in the car mate, like via an octane wire on the l8 (thats how I do it on mine and what he is looking to replicatae) but what he needs to know is:

Do the L6 ecu's have octane wires

If so, what values do MSD put against each wire (stu will need to answer that)

and if the wire is grounded does it have an effect only when the ECU is turned on, or can he connect and disconnect the wire from earth while the engine is running and see the timing come in and out.