Installing a Kenwood KOS-A300 in a 2002 Prius

Hey everyone, I'm new to the forums and I'm considering purchasing an old 2002 Prius w/ high miles. If you have any advice for me on that purchase, search for the thread "Considering paying cash for an '02 with 255K miles for $3800" and leave a post there.

I have a question about a possible aftermarket audio add-on solution for the '02 Prius. It doesn't seem like installing a full aftermarket head unit is practical in this model. I know I could probably make something work with the space where the CD player would be hidden away (if it had one) but I like to see what's playing and I think that would be pretty low to my field of view.

There is a device that Kenwood sells called the KOS-A300 that allows the hookup of an iPod/iPhone via USB as well as XM and Bluetooth with separate modules, some of which I have from an earlier Kenwood setup. It's meant to augment a factory stereo while being wholly separate from it. As I can't post links yet you can search the kenwoodusa website for the model number for more info if you wish. It runs audio out to RCA that I could use a cassette adapter to bring straight into the older system. I know I could use something like a VaisTech SL3U for a more elegant audio connection but the Kenwood device is only $50 at Crutchfield right now and the savings has inspired me to keep it cheap. You control the various sources via a wired knob that can be mounted permanently in the dash/console/wherever or just mounted with double-sided tape. Same goes for an LCD display unit that shows you what's playing and what you're doing. Apart from auxiliary input, it's not meant to interface with any other factory stereo electronics but it does of course need to be hardwired to the car.

I briefly skimmed the product manual to try to see how the main unit is wired to a car for power, and I see how it requires wiring to the leads for the battery and ground (of course), but also the ignition, TEL mute switch, and dimmer control. I'm familiar with finding and attaching these wires in a standard wiring harness, but since there isn't a head unit to remove to get to them, I don't know how I could hook this up. I'm of course wary of approaching any custom stereo installation without being fully informed, as it could cause major damage to the hybrid vehicle. Does anyone have any advice on how I could do this installation, or resources they could point me to about the wiring? Thanks.