I posted that the trick is to use the guide pins on the engine that are meant to hold the tabs on the plug boots...they line up perfectly with the hole for the plugs...and the boot itself you are trying to insert down there has a little hole in its tab that matches the guide pin...meaning you have a three dimensional set of reference points, with depth, and alignment.

I can now get the plug on w/o looking (Used a remote robot camera the first time, and a mirror the second time...) by just using the guide pin reference points....(2) 6" extensions and one universal joint.