Stock radio....anyone know how to....

["Turbo-T"]

....take a stock radio and set it up with a small 1/8 jack for IPOD or CD?

Example of one I found on eBay:

According to the seller, they say:

This aux input has been hardwired into the amplifier
of this stereo.

Here's how it works!

Simply plug in your 3.5 mm cord. This overrides the audio signal and allows input from the aux port. Simple Plug n' Play!

I know someone on here found a way to do this by tapping into the tape head but the tape mechanism has to be engaged for it to work. it looks like with this set up it is not required to engage the tape mechanism.

I have a spare Delco AM/FM/Cassette I'd like to do this to w/o paying the typical $200 + one of these "retrofitted" radios typically goes for.