What Martyn was saying is that we have a automotive dedicated forum on http://www.picoauto.com/support/ that you can ask automotive related questions, whereas www.picotech.com is aimed more at our T&M customers.
That said, in order to stabilize and identify each cylinder you need to enable a trigger, and then trigger on cylinder #1. You can do this by connecting the trigger out from the Mixmaster (far left BNC on the bottom row of the Mixmaster) to a channel on the 4423 and then in the software changing the trigger settings from None to the channel you connected the trigger out to. You will have to play with the trigger threshold some, depending on the output of the coils.
Now you should have a steady signal on the screen. The yellow diamond on the screen indicates the trigger point, and also #1 cylinder. You can click and drag this point on the screen to move the signal left or right. Now that you know this is # 1, you can use the firing order and go right to determine the other cylinders (so on a Chevy 350 the ignition event to the right would be #8 since the firing order is 18436572).
Steve,
With your help I have understood what was going on. I now see which one is #1 because, indeed, the grayed-out diamond designates the starting firing order.