Did this repair yesterday. What a pain in the (removed) for a $4 O-ring!! Here is my contribution:
It went very well start to finish thanks to the advice in this thread. Took me over 3 hours but part of that was trying to find tools that would fit in the tight clearances, and taking relaxation breaths and I delved deeper into the job. I am very much a novice.
The prep work and tear down was the hard part...getting it installed and zipped up was a breeze.
It went just as expected with a couple minor exceptions. First, the wire bundle and power steering line as they pass along the wheel well had to be scooted out of the way to access the tensioner bolts. I know I had seen some mention of ps lines in the way but this was not where I expected it. I had to get a razor blade and cut the tape that secured the bundle to the plastic bracket on the wheel well, and had to pull the other tubes out of their brackets to wiggle a socket in there.
The second near snafu was when I removed the tensioner from the block. It was stuck on there pretty good- I ended up using a pipe to catch the little exposed lip and whacking it with a hammer. The tensioner went flying back into the oily abyss. I had get under the car and just feel around above the crossmembers and axle. It dropped it a few times (slippery!) as I blindly tried to guide it out. Finally went up top and was able to spot it and extract it with a magnet/ grabber tool I picked up at Walmart the night before.
Here's the cleaned up tensioner with new O-ring. Notice the red bungie holding my v-belt in place- sage advice from one of my sources...
I did use some RTV on the flange. So far, it's dry around the repair, though still some drips on the floor from the area. I'm not sure I don't have another leak somewhere, or it could just be residual oil finally working it's way down, or dirty brake cleaner that has dripped down. Time will tell.
Here are some other links I used in case anyone else on interested.
http://www.toyotanation.com/forum/showt ... ?t=1556962
By the way the Matrix users link above is recently dead.
Huge THANK YOU to all who posted about this!!