I've figured out a way to add AUX to the 2001 TL 's stock radio by hacking the radio itself. It is free, no external adapters are needed.
But you will have to sacrifice one of your inputs: CD, FM/AM or TAPE and will need somewhat advanced soldering techniques as well as a fine tip soldering iron.

Basically you need to open the radio by removing the top cover, you will see the CD player module at the top, then unscrew the bolts on the sides, disconnect the CD module from two connectors, connecting it to the face plate and from one connector at the bottom, connecting it to the tape module. Flip the module over. You will see an easily accessible IC: SN761026. This is an audio processor unit and in the same time an input audio channel multiplexer.
The connections are as follows:

TAPE IN: pins 2/47 for left/right
FM/AM IN: pins 3/46 for left/right
CD IN: pins 4/45 for left/right
CD changer pins 5/44 for left/right

Now the hack is obvious. Lets assume we are going to sacrifice TAPE:
1. Heat up and lift the pins 2/47 and 5/44 from the board
2. Connect (by soldering wires) the pads on the board for pins 5/44 to the pins 2/47.

Now every time you select tape from your stock radio, your CD changer audio in will be selected and routed to the amplifier instead. All you need to do now is solder your aux wires to the CD changer 14 pin connector located on the back of your radio: pin 2 - right channel, pin 9 -left channel, pin 12 is ground.

This may be a bit of an extreme hacking, but why not give it a try, if having an AUX is all you want, and you can achieve that without buying an adapter or an aftermarket radio.

 

nice... I am sure nobody will be sad to see the TAPE input disappear. lol

 

got any pictures you can post up? My cd player is busted so If i can change this out for the cd or cassette i wont even bother getting a new HU.

 

Cool, I just can't really understand why Acura didn't put a aux input from factory.. Strange?!