I had installed this unit in my F-150 and it wasn't too bad. In the 4 runner, you'll have to take apart half your dash and center console. I just installed the Alpine W200 this weekend. You will use the existing factory brackets and you may or may not need to modify them. You can throw away the sleeve. See this thread regarding the brackets:
http://www.toyota-4runner.org/showthread.php?s=&threadid=23041
I'll post some pictures and more info regarding the bracket issue tonight when I get home.
Did you get the Metra trim kit brackets? You'll need them to cover the gaps on the sides of the HU.
You'll need to tap into the vehicle speed sensor and parking brake lead. Parking brake lead is light green wire, pin 1 on 20 pin connector at bottom left of your fuse panel under driver side dash, near the door.
Or (thanks to tarheeltp17)
- speed sensor is purple/red at the ECM, 2nd plug from bottom, pin 8 . ECM Is behind the glovebox.
- Parking brake is lt. green at the Body ECU, middle plug, pin 2. BECU Is on the driver side under the dash.
- reverse is red/yellow at the left of fuses, 16 pin plug.
Have fun... I've done a dozen or so installs in my time and I have to say my 2005 4-runner was by far the biggest b!tch (of course, I have the JBL, so that complicated my situation with having to bypass). Enjoy the D1... it's a solid unit.