Problems by replacing the Sxara Picas CD radio

So, the radio/CD player in my Xsara Picasso (it's a 2002 model) has broken down. I had one from my old car, and when I installed it, I lost the steering wheel controls and the trip computer.
I suspected the steering wheel issue, but the trip computer problem caught me completely off guard. Do you know if there are any cables that need to be disconnected, replaced, or bypassed to get the trip computer working again?
Can the Picasso's CD player be replaced without causing these problems?
Thanks