Ok so:
1)You need enstones CCapi installed if you want to use that on CEX. Search NGU its simple
2) Next you need to open the application and on the ps3 go to settings and system info to find you're IP address. (Or any Homebrew that let's u see you're ip.)
3) Load up the game on ps3
4) On the tool click connect with CEX and type in the IP from the ps3
5) Go to a private match and press attach
6) Enjoy!!!!!
Hope I helped
xShaTTer