E46 cd autochanger

[paf291x]

Hi guys i am looking to fit a cd changer to the boot of my 318 touring on a 2003 reg the head unit is a business and the leads that i have in the boot include one 4 pin connector and one 2 pin connector i can't find a serial multi plug so:
1) is this plug needed on a 2003 plate
2) do i have the correct leads to connect a changer
3) where can i get the relative equipment needed including the changer

All Help would be greatly appreciated thanks Paul....

[paf291x]

I was looking to fit a bmw 6-disk autochanger to the boot.

[paf291x]

thanks guys for the information its a big help only one more question can you still use the steering wheel controls with the i-pod ?