CD changer connection

[still in61]

Hi
I have a french supplied LHD Megane 1 and want to connect a underseat Alpine 6 cd changer from a scrapped RHD
My cable to connect to the back of the dash header unit must have a male rectanglur connection - but it has a square one
Any ideas? Can I get a wiring diagram and put on a new male connection?
Thanks
Bon Noel