The 5D MK II does not have the electronic grid display that came out later on the 7D. However, unlike the 7D, you can replace the focus screen with various ones that do have different or even custom grids
Canon does not make a focus screen with a rule of 3rds grid, this is what they have.
http://www.bhphotovideo.com/c/product/590409-REG/Canon_3356B001_Eg_D_Precision_Matte_Focusing.html
Third party companies do take canon focus screens, and add grids to your requirements for a price.
http://www.brightscreenstore.com/store/