I installed my TRD springs today. It wasn't very hard to do. Anyone with some mechanical skills and the necessary tools should be able to do it.
I thought I would do a little write-up with pictures. I'll start with a list of tools and a few tips/suggestions/warnings.

Here are a few tips for you. A few days before you start the spring install spray all of the nuts and bolts with PB Blaster or some other penetrating lube. Some of the nuts were already rusted. You will need the hex keys for the stabilizer bar end links. They are a PITA to get off. The keys fit in the end of the threads on the end link ball joint. Then you use a wrench to remove the nut. you need four hands to put the rear struts back in. It is really tough to get the three studs to go back in the top mount. Then you have to hold the strut up while fiddling with the nut that you can't even see. Mark everything with tape and/or a marker. It makes it much easier when reassembling the struts.

This is a list of the tools you will need and the different size bolts/nuts and their locations.
1/2" breaker bar
1/2" drive ratchet with extensions
3/8" drive ratchet with extensions
metric sockets for both
jack and jack stands
compressor and impact gun (not necessary but it makes it easier)
hammer
screwdrivers
torque wrench
spring compressor (Autozone tool loan)
5mm and 6mm hex keys (these are a must)

Rear
10mm 12mm for brake line and speed sensor
19mm for top nut and lower strut bolts
12mm for side bolsters on seats
12mm for 3 nuts on top strut mount
14mm for sway bar end links
5mm hex key for end links

Front
22mm for lower strut bolts
19mm for top nut
14mm for 3 nuts on top strut mount
17mm for sway bar end links
6mm hex key for end links

Remove the rear seat bottom and unbolt the side bolsters of the rear seat back. I have an LE the SE and XLE have different rear seats.
This is the rear upper mount



Jack the rear of the car and place jack stands underneath
Remove the rear wheels


Remove the speed sensor bracket and the brake line bracket
Loosen but don't remove the top nut on the strut
Place a jack under the lower control arm
Remove the swaybar end link nut from the strut
Loosen the two bolts on the lower mount
Mark the stud and its position so it can be reinstalled in the same location
Remove the three nuts on the top mount
Remove the lower bolts and gently lower the jack and remove the strut
I marked each of the struts with tape so that I could line everthing up during reassembly

Compress the spring and remove the top nut
Compress the new spring and place it on the strut
Attach the top mount and tighten it down(don't forget the spacer)
Reverse the installation procedure

Raise the front of the car and place it on jack stands
Take off the wheels



Remove the speed sensor bracket and the brake line bracket
Unclip the speed sensor wire plastic bracket from the strut
Loosen but don't remove the top nut on the strut
Place a jack under the lower control arm
Remove the swaybar end link nut from the strut
Loosen the two bolts on the lower mount
Mark the stud and its position so it can be reinstalled in the same location
Remove the three nuts on the top mount
Remove the lower bolts and gently lower the jack and remove the strut
I didn't get any pics of the front strut but it is very different from the rear struts. The spring in the front is installed on an angle. It is a little harder to compress. Also the top mounts are multi piece and contain a bearing. Be sure to assemble this one correctly.

Here is a before and after