I have a Renault 2 phase one Laguna Sports tourer and have just fitted a cd changer. After several enquiries on the net I went to a company that advertises on this forum. I installed mine in the boot out of view, the company supplies a lead that fits directly into the supplied car radio so you are able to use the control stalk on the steering wheel column.
Details of the cd changer purchased : 1 x Renault CD Changer (PACK 4 - VDO Dayton) (RENCD-KIT7) = £143.97
Company: ADD A CD Changer
ADD A CD Changer | MP3 CD Changer | Car CD Changer UK
Have a look at the website they have two cd changers that are compatable with your car.
If you do decide to fit one in the boot I would suggest that you release the car radio from the dashboard but do not disconnect.
A word of warning is that it is recommended that you disconnect your battery before working on this but I fitted it by just ensuring that the ignition key card was not in place.
I then removed the inner glove book which gave me access to the rear of the dashboard where the radio sits I was then able to route the lead along the passenger side of the vehicle hiding it by just pushing up behind the trim and then into the boot area.
Sounds a lot but I didn't take very long. They also supply full fitting instructions with the cd changer unit. This unit also plays MP3 CD's. I used a programme to convert many of my original
CD's to the MP3 format so even more music is available with this 6 cd changer.
Hope this helps and if anything needs any further information let me know.