Just changed my rear struts tonight and figured I'd share my experience in case others are planning to do this in the future. Ordered KYB replacement parts (all from tire rack as listed earlier in this thread), OEM coil springs, and replacement bolts for the sway bar link from Lexus directly. I had a mechanic assemble the struts and coils together, since I didn't really want to risk using a spring compressor.
Anyway, to the install. The car is a 2004, has 240,000 miles, and lives in Maine. Everything was totally rusted out and all I can say is thank god for air tools. The bolts holding the strut to the knuckle were, as expected, extremely tight and having an air impact wrench makes all the difference. It was not seized on so I'm positive it could have been done with hand tools. However, I ran into two problems through the process.
First problem was the sway bar link nut. It is an allen key surrounded by a 14mm nut. After 11 cold winters of salt, the allen key completely stripped and rusted out, no chance of having that work out. Had to heat with a torch, hold the back of the sway link (behind the strut mount) and go to town on the nut with the impact wrench. This was the only way I could get it off and was glad I picked up replacement bolts. Reinstall was the same process. Hold the sway link from behind the strut with pliers, tighten the nut with impact wrench.
Second problem (not really a problem, but) was aligning the knuckle with the strut. Had to use a combination of screw drivers to pry the strut into position while hammering down on the knuckle to get it to sit properly. Not the hardest thing to do, just takes patience and fiddling to fit it into place.
All in all, I do think this is doable for the average DIYer. Southern cars will be much easier to do this as dealing with rust and seized bolts was the most difficult part. In the end, it's only 7 bolts and the strut drops out.
Check out this youtube video I used as a reference. It is done on a highlander, which is essentially identical to the RX330.
I hope this helps someone who wishes to tackle this project. I'm happy I did! Good luck!