Whaler,
Try this. Can you trace out the other end of the IGN SW Coil wire? From what you are telling me I am assuming that it's just a short wire that runs from the 'IGN' terminal of the switch directly to the coil to provide the 12V when the ignition switch is energized. If this is the case, you're all set. Just wire the one end to the ignition switch and the second end to the small red MSD wire (the 'switched power' wire, as MSD refers to it). Wire in a toggle switch if you like, somewhere inconspicuous, so it's not easily found. Let us know where the second end of that wire goes. If it's a painless kit, I believe it will say
PPI or something to that effect directly on the fuse block. Does it? We'll get to the bottom of this yet
...
Mike