Instead of going thru the process of installing a jack and all that, I just cut one end off a male-male audio cable and soldered it to the board of my 06 Tundra CD player.
The process basically consists of:
Removing the cdplayer from the dash
Disassembling headunit by removing 20-30 small screws
Separating CD player from control unit
Locating correct channel solder points
cutting the end off one 4ft 3.5mm audio cable, stripping the wires, soldering them to the board.
reassemble cd player unit
A CD must be in the player. When nothing is plugged in, the cd player works as normal. When I plug any audio source into the wire it picks up that signal and overrides the CD player output, giving you an aux input.
Their is no static or interference whatsoever except for when the phone is charging by the cig lighter. When not charging the sound quality is higher and cleaner then most CD's and is loud enough to damage the factory speakers.