You can try looking on the website of the company who made the CD player - but this could be expensive.
Your best option is to try a company called Autoleads - available from a retailer (Halfords etc) or the internet, and around half the price of the genuine parts.
The leads come in two parts - one specific to the car, one specific to the brand of CD player (so if you change either your car or CD player in the future you only need to buy one of the two parts again)
I fitted a Kenwood CD to a Citroen, the leads cost around £27 for both sets, and they work perfectly. The same cables from Kenwood were £50-60,
If you can fit a normal stereo, this will add about 2 minutes to the job.
Pitmonster, February 2009