Poor man's iPhone remote control on non-NAV cars

I bought a Package III without NAV. As such, I cannot control the Turn off signatures in Tapatalk the steering wheel controls, as this vehicle lacks the A2DP feature. I use a 1/8" male-to-male audio cable to connect the iPhone headphone and AUX ports.

What if:

I buy the Apple headset with remote control:
Walmart.com: Apple iPod/iPhone Earphones with Remote & Mic: Audio

Snip off the ear-buds. solder the L, R, ground wires to the 1/8" audio cable (I snip off one end of the following cable):
Griffin 1/8" Auxiliary Audio Cable for iPod® and iPhone™ - RadioShack.com

Now I have a audio cable with remote control that plugs into the iPhone headphone jack and into the Prius AUX jack.

I can leave the iPhone in the armrest, plug it into the 12V (with appropriate cable) for charging, use the cable rigged above (with the remote control part hanging out of the armrest) for pausing and skipping songs.

Phone calls get handled by the handsfree BT feature built-in into the Prius III.

Voila! full featured iPhone/iPOD connectivity for $40.

[Admittedly, the remote control of songs is not on the steering wheel, but at least it is accessible without fumbling around with the iPhone]

Aloke Prasad
PS: which parts of the 1/8" jack (on the shaft and tip) are for the L, R, ground connection?