Well, I got it done. Had to wait for the wife to get home from work with the van so I could go to AZ to rent the tool. Between that and eating dinner, I finally got done. It worked, but I had to get to it from the top. The tool was so long that it contacted the lower control arm and there was no room to relieve tension.
This mod is a serious PITA on an ATX. The only way I could "lock" the engine was by using a socket and driver on one of the torque convertor to flexplate nuts. It took a lot of muscle to break the factory torque on the damper bolt.
I could't find the correct bolt for the installation tool, either. So, I ended up using both washers, various sockets, a box end wrench, and even the key to my locking lug nuts to make the bolt fit. It was a bit too short, but long enough that it would bottom out in the crank with certain socket/washer combos. At one point I even had a socket in a socket, using the larger one as a washer, lol.
Perhaps it should be added to the FAQ that you will need access to the torque convertor to flex plate bolts for ATX cars, and Pre-98 cars will have clearance issues and will need to rent or buy a belt tensioner tool from Auto Zone.
Oh, and I do notice a difference in the engine, though not as dramatic as some here would suggest. Perhaps it is because I have an automatic and the fluid filled torque convertor might act as a bit of a damper? (Fluidamper, anyone?

). It would be interesting to see the number of engine failures for MTX cars vs ATX. I'd be willing to bet that the ATX cars are far below MTX's in failure rates. My engine failed, but I believe that was due to shoddy workmanship at the dealer when they fixed my oil leak (front main seal). I think they turned the engine counter clockwise and bound up the timing chain.
Anyway, I used to feel a slight vibration in the floorboards above ~3200 RPMs. Now it is gone and the engine is electric motor smooth. Very nice indeed, well worth the mod.