what i have done on my laguna 2, is to fit a cable from the amp unit which is located in the boot space on mine. iv run through the car to the centre console. it runs through the aux setting on my cabasse system and i can plug any mp3 ipod etc into it using the 3.5mm jack. i had the cable off ebay
, cost about £23. the guy selling them was really helpful and is able to custom make different leads for different systems. just do a search for renault radios or aux in etc.
the sound is fab with mine. bit of a faff putting it in but worth the effort.