I just installed the USA SPEC pa15-toy into my 2006 Toyota Avalon. I have the following:
2006 Toyota Avalon Touring
6 CD JBL Stereo w/ Tape
no factory Sat
no factory Nav
I was able to get the unit working and charging the iphone/ipod with steering wheel controls. I was UNABLE to get the TEXT display working correctly. After working with the USA SPEC tech support, I was unable to get this feature working correctly, even though the website states TEXT works w/ all stereos that have a "TEXT" button, etc. If I set the unit to work like the SAT, I could get TEXT, but I couldn't switch back to the ipod mode, if I switched to something else like FM, CD, etc. I am wondering if Avalons w/ the factory Sat work properly with TEXT. Other than the TEXT issue, the system works great and the g/f loves it. Also the sound is amazing compared to the tape cassette adapters.
I read that most people installed the systems wired it to the glove box. I didn't think this made nearly as much sense as running into the compartment in front of the armrest that looked like it was purposely built for a mp3 player. I wedge the pa15 module inside the center console between the backseat AC duct and the shifter. I removed the 12v module from the compartment drilled a hole large enough to fit both a RCA-Phono cable and the ipod cable. I ran enough cable for each to allow the device to be easily accessible from the driver. I then replaced the 12v module back in and put everything back together.
Guide:
---Disclaimer----
I am not a car mechanic or an electrician, it is suggested that you disconnect the ground from your car before you start. Do this at your own risk!
First I removed the front cover by using a putty knife I wrapped with tape to prevent damaging the surface. To remove the cover put the putty knife under each corner and push it up. Note that the cover goes a little under the cover in front of the driver
I then removed any items from the two center cabinets as well as the carpet bottoms. After removing the carpet bottom of the armrest cabinet, I removed the two bolts attaching the cabinet and pushed it back to allow for better access of the smaller cabinet.
I then removed the nob off the shifter and took off the plate w/ the P, D, R on it. I then removed the cover that would normally be where heated seats are
I then lifted up the whole top cover for the center console and rested it on the shifter nob. This allowed me access to the screws that hold the small cabinet to the center console.
(holes for screws on the top and bottom right of this picture)
I then disconnected the power cable to the 12v module
After that I removed the 12v module from the plastic bracket by using a small screw driver to hold the tab up, while I pushed the module into the small cabinet.
I then pushed two retaining clips on both sides of the 12v plastic bracket and pushed it into the cabinet:
I then used a 1/4 inch drill bit and drilled a hole on the bottom passenger side of the 12v opening. I then pulled the two cables into the cabinet:
I moved the AC controls to the side and unscrewed the 4 bolts holding in the radio. I removed the radio unplugged the CD Changer and fished/ran the cable that connects the pa15 Y-Adapter to the pa15 module. I plugged the cd changer into the Y adapter and the Y adapter into the radio. I then placed the pa15 module in between the shifter and rear AC air duct:
I entered the correct settings for the dip switch tested it and then closed everything up and lived happily ever after.
I took these pictures when I was a good portion through the project as an after thought.
And the finished product...
If anyone find this helpful, let me know.

-Hostage