I want to set my DJM 900 crossfader to control the crossfader in traktor pro 2

Can someone help me do this? Basically I want to record my live mixes using Traktor's recording when I'm using CDJ's and DJM900. When I scratch with my CDJ with traktor I want the DJM to move the traktor crossfader. IS THERE info out there that will help me step by step perform this setup?

Thanx
DJSixx