steering wheel remote

Having adapted my beat-up old car stereo to take an iPhone 3g input (with a wire trailing from the input jacks round the back of the stereo), I am v happy with the sound coming out of the car when I play music through the phone.

I would like to control some basic functions of the iPhone with a steering wheel remote - mostly skip to next track, play, pause, and answer phone call (with speakerphone) and hang up (returning back to the music).

Is there anything that can provide just this functionality? The Kensington liquidaux may be an option but it does too many other things and I want as decluttered (but cheap!) a solution as possible. It also doesn't let you answer calls through pressing a button on the remote does it?

The head unit is bypassed completely! The lead connects to the back instead. The back of the unit (some Sony, about 15 years old) has 2 standard phono inputs. Those were connected to a CD changer in the boot. I unplugged that and stuck the lead for the iPhone in (looks like this) .

There is a tiny gap at the bottom of the car stereo, which was enough for the wire to come through though I did have to push quite hard to get the unit back in. The wire (ending in headphone jack) pokes out of the bottom of the front end of the stereo and I connect this to the iPhone. The stereo does not have a aux-in or miniaux-in on the head-unit to plug the iPhone into.

Sound wise, it is excellent and probably better than any cassette adapter or FM transmitter. So I just need a safe way to control the iPhone (skip, answer calls) while driving. I was hoping some company would have come out with a remote for this. I know there are car remotes for iPods, and bluetooth car kits that could control either the iPod functionality or the ability to handle calls hands-free. But I don't know of any remote that allows both.