I have a 2007 Limited V8 with the factory nav system, and had to buy the following to get XM (about a year ago):
- 86180-0W030 RCEIVR, XM SDAR ($218.90)
- PT546-89060 FITKIT, XM, 4RUNR ($113.30)
I bought these at Liberty Toyota in Colorado Springs, and they charged me $150 labor for the install. The service writer told me when I picked it up that mine was the first they had done, and they were just guessing when they quoted me the labor. He said it took longer than he had expected, and they would charge more labor next time...
I think the receiver is installed under the passenger seat, and the antenna is on the roof by the rear hatch. I am not real happy with the antenna mount, as when I am driving at interstate speeds or there is a strong crosswind, I get a buzz/rattle from the wire vibrating against the roof. I suppose I can just tape the wire down (it is totally hidden by the spoiler), but I think I will make them fix it next time I am in for service.
The XM is integrated pretty well with the nav system, though there are only three presets you can access with the "Mode" switch on the steering wheel. And you have to tune the XM channels with the knob on the nav, as the up/down tuning switch on the steering wheel just resets the selected preset to channel 1. And when you select the text screen to see the current song and artist, it often truncates the name if there are more than some modest number of letters.
The sound quality is extremely good.