It depends if the original purchaser of the game used the codes for the Ferrari CS.
I got Forza 2 Collectors and the code is input into the 'redeem code' thingy on the dash, and it's then added as a purchasable car within the game, which you buy in game with credits. If the code has been used, it can't be used again.
So, if the guy who bought the game originally used the code, you will not be able to. The code may not even be in the box. If the guy bought it, and never used the code, you will be able to use it. I would suggest the original purchasr did use the code, as the extra cars were pretty much the only reason to get the LE.
All that said, if you really, really want the Ferrari CS, just buy the 'normal' version of Forza 2 and once you have played it, send me a Friend Request. As i said, the CS is added to the game once the code is input, and once that is done, you can buy as many CS's as you want providing you have the in-game credits.
I will buy you a stock Challenge Straddle, then gift it you through Forza 2.
Edit - i have done this before (i.e. gifted a Ferrari CS to a friend who did not have the LE) although that was about 8 months ago, so i don't know if a patch was released to stop LE cars being gifted. But as i say, last time i did it, it worked, so if you want the CS and assuming it still works, i will send it