Standard audio system - upgrading it

[jct]

I took possession of my sparkling new british racing green cooper s last week. I would like to be able to listen to MP3's in my car.
I've seen several other threads here on this topic, but none wth this particular bent.

Is there any way to hook up an aftermarket mp3 player in the trunk. Ideally, I would like to be able to control it from the already installed default stereo. Even better would be to have it controllable from my multi-function steering wheel.
I don't care if the mp3 player reads from cd's or has some sort of hard drive, so long as the capacity is relatively large.
Living in Canada requires long driving times to get to interesting places, and the radio here is terrible.

[12lee]

Dension DMP3 interfaces to the Mini's head unit and emulates a changer. Do a search on "DMP3" in mini2.com for more info. Capacity is whatever 3.5" HD you decide on and it responds to keypresses from the head unit and therefore MFSW.